动词时态典型易错题分析-04

【典型考题】He is very busy. I don’t know if he _____ or not tomorrow.

A. come                                                   B. comes

C. will come                                             D. is coming

【易错陷阱】此题容易误选B。认为 if 引导的是条件状语从句，从句谓语要用一般现在时表示将来意义。

【思路分析】其实，此题答案应选C，句中if引导的不是条件状语从句(即if≠如果)，而是宾语从句(即if＝是否)，句意为“他很忙，我不知道明天他是否会来。”请看以下类似试题：

(1) I don’t know if she _____, but if she ____ I will let you know.

A. comes, comes        B. will come, will come

C. comes, will come     D. will come, comes

答案选 D，第一个 if 引导的是宾语从句，第二个 if 引导的是条件状语从句。

(2) “When _____ he come?” “I don’t know, but when he _____, I’ll tell you.”

A. does, comes         B. will, will come

C. does, will come      D. will, comes

答案选 D，第一个 when 疑问副词，用于引出一个特殊疑问句；第二个 when是从属连词，用于引导时间状语从句。

(3) “When he _____ is not known yet.” “But when he ____, he will be warmly welcomed.”

A. comes, comes         B. will come, will come

C. comes, will come      D. will come, comes

答案选 D，第一个 when 引导的是主语从句，第二个 when引导的是时间状语从句。