During the race many cars ______ while my new solar car came out first.

A．broke out

B．broke away

C．broke down

D．broke up

函数fun的返回值是（） fun(char * a, char * b) {int num＝0,n＝0; while( * (a＋num) !＝'\0') num＋＋; while(b[n] ) { * (a＋num) ＝b[n] ;num＋＋;n＋＋;} return num; }

A. 字符串a的长度

B.字符串b的长度

C. 字符串a和b的长度之差

D.字符串a和b的长度之和