When it comes to modern communication, network safety is always a major          . 

concern

advantage

opportunity

solution

考查名词辨析。句意：当涉及现代通信，网络安全一直是一个主要令人担忧的问题。A. concern关心，令人担忧的事实或情况；B. advantage 优势；C. opportunity 机会；D.solution解决方案。网络安全一直是现代通信的个主要令人担忧的问题。故选A项。

All we need          a piece of advice on how we can improve our time management.

are

is

were

was

考查be动词和时态。句意：我们需要的只是一条关于如何改进时间管理的建议。分析句子可知，说明一般情况应该用一般现在时，这句话的主语是All we need, 所以为主语从句，当主语从句作主语时，谓语动词用单数，所以用is。故选B项。

Jenny was very sad over the loss of  the photos she had shot in Canada,          this was a memory she especially treasured.

as

if

when

where

考查连词辨析。句意：珍妮对失去她在加拿大拍摄的照片感到非常悲伤，因为这是她特别珍视的记忆。as 引导原因状语从句，表示“由于”；if“如果”；when“当......什么时候”；where“在哪里”。根据句意，前后文是因果关系，故选A项。

Great amounts of water            poured into the river from the factories two years ago.

was

were

has been

have been

考查时态和主谓一致。句意：两年前，工厂将大量废水排入河中。根据two years ago 可知，句子使用一般过去时。....amounts of修饰不可数名词作主语时，谓语动词用复数形式，即谓语动词与amounts保持数的一致。故选B项。

How I wish every family         a large house with a beautiful garden!

has

will have

had

had had

考查虚拟语气。句意：我多么希望每个家庭都有一个带着美丽花园的大房子！此句是wish 引导的从句，从句要用虚拟语气，根据wish 可知是与现在事实相反，从句一般用过去时。故选c项。