Question

When he saw a little boy ______ in the river, he took off his shirt and jumped into the water.

A．struggles

B．struggling

C．to struggle

D．struggle

Answer 1

B

see sb doing sth “看见某人正在做某事”句意为“当看到小男孩在河水中挣扎时，他脱掉衣服跳进水中。”所以选B。