题目

—What did you do during your summer holiday? —I spent my holiday _______ English in Summer Classes. A.improving      B.improves         C.to improve        D.improve 答案：A用手捏心脏各腔，感觉哪一个部位肌肉最厚（ ）?A．左心房B．左心室C．右心房D．右心室