watasi ha tosyokan de hon wo yomu toki, megane wo kakemasu.

は marks 私 as the topic of the sentence.

So 私は means something like:

• As for me,
• I

It does not just mark the subject mechanically; it sets up what the sentence is about. In this sentence, the speaker is talking about their own habit or action: As for me, when I read books at the library, I wear glasses.

Japanese often uses は where English would simply use I.

Here, で marks the place where an action happens.

• 図書館で = at/in the library
• It tells you the location of the action 読む (to read)

A useful contrast:

• で = where an action takes place
• に = destination, existence, or specific point in time in many cases

So:

• 図書館で本を読む = read a book at the library
• not 図書館に本を読む

を marks the direct object of the verb.

In this sentence:

• 本を読む = read a book / read books

The thing being read is 本, so it takes を.

This is one of the most basic Japanese patterns:

• Noun + を + Verb

Examples:

• ご飯を食べる = eat rice / eat a meal
• 映画を見る = watch a movie
• 本を読む = read a book

Before とき, the form of the verb helps show the timing relationship.

• 読むとき = when I read / when I am about to read
• 読んだとき = when I read / when I had read / after reading

In this sentence, 本を読むとき naturally means when reading books or when I read books in a general sense.

A very useful guideline:

• dictionary form + とき → the action in the とき clause is not yet completed at that point, or is viewed generally
• past form + とき → the action is completed before the main action

So:

• 家を出るとき、鍵を持ちます。 = When leaving home, I take my keys.
• 家を出たとき、雨が降っていた。 = When I left home, it was raining.

It can often feel like either, depending on the context.

In this sentence, 本を読むとき、眼鏡をかけます can be understood as:

• when I read books, I wear glasses
• while reading books, I wear glasses

English chooses between when and while more sharply than Japanese sometimes does. Japanese とき is flexible and often just means at the time of.

So the exact English wording may vary, but the Japanese is natural either way.

The comma is there because 本を読むとき is a time clause placed at the beginning of the sentence.

So the structure is:

• 本を読むとき、 = when reading books,
• 眼鏡をかけます。 = I wear glasses.

The comma helps readability, just like in English.

It is often written, but not absolutely mandatory in every casual context. Japanese punctuation is somewhat flexible, especially in informal writing.

Yes, かける is a very common verb with many meanings. Here it means:

• to put on something worn on part of the body, especially glasses

So:

• 眼鏡をかける = to wear / put on glasses

This is a set expression. Even though English uses wear, Japanese uses かける specifically for glasses.

Other clothing uses different verbs:

• 帽子をかぶる = wear a hat
• シャツを着る = wear a shirt
• 靴を履く = wear shoes
• 眼鏡をかける = wear glasses

So you should learn 眼鏡をかける as a natural collocation.

Because in Japanese, かける can refer either to the act of putting glasses on or to wearing them, depending on context.

In a habitual sentence like this one:

• 本を読むとき、眼鏡をかけます。

the meaning is usually I wear glasses when I read.

It describes a regular practice, not necessarily the exact moment of putting them on each time.

So context determines whether English should be:

• put on glasses
• wear glasses

Here, wear glasses is the most natural translation.

Yes, very often.

Japanese frequently omits subjects when they are clear from context. A very natural version would be:

• 図書館で本を読むとき、眼鏡をかけます。

This still easily means When I read books at the library, I wear glasses, if the speaker is talking about themselves.

Including 私 is not wrong, but it can sound slightly more explicit than English learners expect. It may be used for clarity, contrast, or emphasis.

Japanese is flexible, but this order is very natural.

The clause breaks down as:

• 図書館で = at the library
• 本を読む = read books
• とき = when

Together:

• 図書館で本を読むとき = when reading books at the library

Japanese puts modifiers before the noun they modify. Since とき is a noun meaning time, the whole clause 図書館で本を読む comes before it and modifies it.

So literally, it is like:

• the time when [I] read books at the library

That is why the verb appears before とき.

It modifies the situation/time of the main action, so it relates to かけます, not 眼鏡.

The meaning is:

• At the time when I read books at the library, I wear glasses.

So the time clause tells you when the action wear glasses happens.

It does not describe the glasses themselves.

Yes.

You may see either:

• 本を読むとき
• 本を読む時

Both are common.

Writing it in hiragana (とき) can make the sentence look softer or easier to read. Writing it in kanji (時) is also completely normal.

Likewise, 図書館, 本, and 眼鏡 may appear in kanji, though めがね is also often written in hiragana because 眼鏡 is visually harder for many readers.

Most naturally, it sounds like a general habit.

Because of the non-past forms:

• 読む
• かけます

the sentence is understood as something the speaker generally does:

• When I read books at the library, I wear glasses.

If the speaker wanted to describe one specific past occasion, the sentence would probably look different, with past forms and more context.

So learners should hear this as a habitual or repeated action unless the surrounding context says otherwise.