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
网友回答
A. struggles
(答案→)B. struggling
C. to struggle
D. struggle
解析： 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。