Breakdown of Resistir la altitud es más difícil de lo que esperaban.
ser
to be
de
from / of
difícil
difficult
esperar
to wait / to hope / to expect
Questions & Answers about Resistir la altitud es más difícil de lo que esperaban.
Why do we use de lo que instead of just que here for "than"?
Why does the sentence start with the infinitive Resistir instead of Resistiendo for "Enduring"?
In English, we often use words ending in "-ing" as the subject of a sentence. In Spanish, the "-ing" form (-ando or -iendo) can never act as a noun like this. Instead, you always use the infinitive. You can think of it as literally saying "To endure the altitude is harder...".
Why is esperaban in the imperfect past tense rather than the preterite?
Could I use altura instead of altitud here?