单选题：根据下列材料请回答2-11题：Allergies happen if our immune system __ when

题目分类：英语六级
题目类型：单选题
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题目内容：

根据下列材料请回答2-11题：

Allergies happen if our immune system __ when there are some intruders like viruses and bacteria.

参考答案：

答案解析：

[A] behind [C] before[B] against [D] within

[A] behind [C] before[B] against [D] within

分类：英语六级题型：单选题

[A] as for [B] far from [C] such as[D] by far

[A] as for [B] far from [C] such as[D] by far

分类：英语六级题型：单选题

[A] engages [B] intends [C] deliberates[D] signifies

[A] engages [B] intends [C] deliberates[D] signifies

分类：英语六级题型：单选题

[A] Good or bad, they are there to stay.[B] Like it or not,

[A] Good or bad, they are there to stay.[B] Like it or not, you have to use them

分类：英语六级题型：单选题

点击播放听力音频： [A] The man is the manager of the apartment buildi

点击播放听力音频：[A] The man is the manager of the apartment building.[B] The woman is

分类：英语六级题型：单选题