针对训练 ()1. Mary is good at math, and she is a careful girl now, but in the past, she often math. A made some mistakes at B. made any mistakes in C. made some mistakes in (B)2. This problem is too difficult, she doesn't know to do A how B what C when D. where (B) 3. He doesn't have a room Alive in B. to live in C. to live D. to live with针对训练 （ ）1. Mary is good at math, and she is a careful girl now, but in the past, she often ____math. A.made some mistakes at B. made any mistakes in C. made some mistakes in （ ）2. This problem is too difficult, she doesn’t know _____ to do. A. how B. what C. when D. where （ ）3. He doesn’t have a room _______. A.live in B. to live in C. to live D. to live with B C B