天然气是一种洁净能源,即使泄漏了也不会爆炸。
参考答案:错
As you can see, the number of students using mobile phones _____ these days. [ ]
A. is rising
B. is being raised
C. have risen
D. have been raised
左心室与右心室在解剖上主要区别是:
A.右心室是心脏最靠后的部分
B.左室室是心脏最居于前面的部分
C.右心室有节制索
D.左室室上右心室的左前方
E.左心室才有 * * 肌