2026年2月托福机经套卷(第4套) - Listen to an Academic Talk / 2 Q3

原题

录音 1

What does the speaker say about chunks of calcium carbonate in concrete?

AThey result from not enough mixing.

BThey enable concrete to repair itself.

CThey can cause concrete to crack.

DThey cannot react with water.

正确答案：B

老师暂未填写解题思路。