泡沫类堵水化学剂，根据成分的不同可分为三相或四相泡沫。
参考答案：错
撒哈拉以南的非洲以______________气候和______________气候为主。
— Where is Jim?
— I have no idea, maybe he school.
A. has been to B. has gone to C. goes to
