can 后面只能接原形动词.至于接几个原形动词合适,要不要加 ing,这要根据句子的长短、是否造成歧义、和语法结构是否允许来决定.例：
John can teach English,help students with math,take care of pre-school kids,and cook meals for them.
John can leave his highly-paid job behind,forget all his friends,say goodbye to his parents,and travel thousands of miles just for climbing mountains.
至于用加 ing的动词,通常出现在两种情况里面：动词的ing 形式作谓语动词的宾语,或者 ing分词短语作主句的伴随状语.例：
John can now handle answering phone calls,sending out signals and managing his own daily life after the accident.（作宾语）
John can walk out of the office without telling anyone,knowing that the boss will not be happy about it.（作伴随状语）