He hadn’t seen his mother for a long time so when he saw his mother he crying.A. burst o

问题补充：

He hadn’t seen his mother for a long time, so when he saw his mother he crying.

A. burst out

B. burst into

C. burst in

D. burst on

答案：

(答案→)A. burst out

B. burst into

C. burst in

D. burst on

解析：考查词组：句意：他很长时间没有看见他的妈妈了， 当他看见他的妈妈就突然哭了。Burst out后面接动名词，表示“突然…”，burst into后面接名词，也是“突然”，所以如果crying改成tears，就可以选B，burst in突然闯入，burst on突然出现，到来，所以正确答案是A。