The teacher as well as the young students ( )engaged in labor

The teacher as well as the young students ( )engaged in labor with great enthusiasm.
A、is
B、are
C、am
D、were
【正确答案】：A
【题目解析】：as well as 也.. 连词，句子的主语是the teacher，因此用单数，句子含义是老师和同学们一样极大的热情投入到劳动中。