Module 4
重点句型
1. They are often so thick that you cannot see the sun, and the wind is sometimes strong enough to move sand dunes.
沙尘暴经常是很厚的,以至于你看不到太阳,而且风有时大得能够刮动沙丘。
2. The storms sometimes continue all day and traffic moves very slowly because the thick dust makes it difficult to see.
暴风有时持续一整天,车辆开得很慢,因为浓浓的尘埃降低了能见度。
3. I can't help but feel very concerned.
我禁不住感到很担心。
4. The garbage is then taken away and, if possible, recycled.
然后把垃圾运走，倘若可能的话，予以回收利用。

句型探究
1. The garbage is then taken away and, if possible, recycled.
然后把垃圾运走,倘若可能的话,予以回收利用。
if possible是if it is possible 的省略形式。当if, when,while,until, unless, once, whether 等引导的状语从句的主语与主句的主语相同，并且从句中含有系动词be时，或从句的主语是it 且含有be 动词时，从句中的主语及部分谓语(be动词)可省略。
If possible, she wants to go with us.
可能的话，她想跟我们一起去。

if引导省略的情况有下列几种：
if any 如果有的话
if necessary 如果有必要的话
if so 如果是这样的话
if ever 如果曾经有的话
if not 如果不这样的话
Inflation may be rising, if so, prices will go up.
通货膨胀率可能上升，如果那样的话，物价就会上升。
He is a great musician, if ever,there is one.
如果曾经有过伟大的音乐家，那他就是一个。
2. I can't help but feel very concerned.
我禁不住感到很担心。
can't help but+动词原形，意为“禁不住做某事”，相当于can't help doing sth.