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