小题1:The English poem is difficult to understand. Could you explain it to me?

小题2:She has formed a good habit of setting aside some money every month.

小题3:Many smokers are well aware of the danger of smoking.

小题4:Measures must be taken to prevent trees from being cut down.

小题5:Helen is very pleased to have travelled in more than 20 provinces and cities in China.

题目分析：

小题1:The English poem is difficult to understand. Could you explain it to me?

本句难点在于当形容词是easy/difficult/hard说明主语的特征的时候，后面的不定式使用主语形式表示被动的含义。

小题2:She has formed a good habit of setting aside some money every month.

本句考查了固定搭配form the habit of养成…的习惯；set aside放在一边，不管不顾，储蓄；收拾，整理。

小题3:Many smokers are well aware of the danger of smoking.

本句考查了形容词短语be aware of意识到…。

小题4:Measures must be taken to prevent trees from being cut down.

本句考查了两个固定搭配take measures to do sth采取措施做某事；以及prevent sb from doing sth阻止某人做某事。

小题5:Helen is very pleased to have travelled in more than 20 provinces and cities in China.

本句考查的不定式的完成式表示在谓语动词之前就完成的动作或者存在的状态。

点评：做这类题，不但要选择正确意义的词、词组及句型，还要根据具体语法和语境，选择适当的时态、语态及使用正确的词形。