Learn Turkish: Bu ürün sadece bir mucize değil, aynı zamanda çok etkili. - This product is not only a miracle, but also very effective.

The full structure is sadece ... değil, aynı zamanda ... (da/de). The da/de (meaning "also" or "too") is optional because aynı zamanda (literally "at the same time") already implies the addition. You could add de after etkili, but leaving it out is very natural and common.

What is the literal translation of aynı zamanda, and how does it act as "but also"?

Aynı zamanda literally means "at the same time" (aynı = same, zaman = time, -da = at/in). When paired with sadece ... değil (not only ...), it naturally translates to "but also" in English because it introduces an additional, simultaneous quality of the subject.

Could I drop aynı zamanda and just use da or de?

Yes, you absolutely can. You could say Bu ürün sadece bir mucize değil, çok da etkili. Using aynı zamanda just makes the sentence feel a bit more structured or emphatic, much like choosing "not only... but also" instead of "not only... and ... too" in English.

Why doesn't etkili have a "to be" suffix to mean "is effective"?