Tom and Mike are good friendsoften help each others.A. TheyB. ThemC. TheirD. Theirs

问题补充：

Tom and Mike are good friends. often help each others.

A. They

B. Them

C. Their

D. Theirs

答案：

(答案→)A. They

B. Them

C. Their

D. Theirs

解析：考查人称代词的用法。句意“汤姆和迈克是好朋友。他们经常相互帮助。”缺少主语应该用人称代词的主格，人称代词的主格用I/he/she/it/they。这里是复数应该用they。故选A。