1．找谓语：一个句子无论是主句还是从句，必须要有谓语。若句中没有谓语动词，或者虽然已有谓语动词，但空处所需词与之是并列关系，空处就用谓语动词。谓语动词需要考虑时态、语态和主谓一致。
2．若句中找到了谓语动词，而又缺关联词(并列连词或从句关联词)时，则所给动词用非谓语形式。非谓语需要考虑v.ing形式、v.ed形式和动词不定式。
[题组一]
①He volunteered to help control traffic，____________(donate)an hour of his time every week.
②He volunteered to help control traffic，and __________(donate)an hour of his time every week.
分析：两句的差别是连词and。分析句子结构可知，①中设空处为现在分词作伴随状语；②中设空处与volunteered并列作谓语。故①填donating；②填donated。
[题组二]
①Jim was listening attentively to the lecture，and all his attention ____________(fix)on it.
②Jim was listening attentively to the lecture，with all his attention ____________(fix)on it.
③Jim was listening attentively to the lecture，____________(fix)all his attention on it.
