根据括号中所给的汉语写出单词。
⑴Those boys like playing hide-and-seek and often hide ____ (在…之中) the trees.
⑵How beautiful she is and her skin is as ____ (光滑的)as silk.
⑶She is looking forward to____ (收到) letters from her friends.
⑷The heavy smog makes it more difficult for us to see traffic signs ____ (清楚地).
⑸After several____ (星期) study, we will have our senior high school entrance exam.
B）根据句子意思，用括号中所给单词的正确形式填空。
⑹In the morning, taking a walk and____ (breathe) some fresh air are good for your health.
⑺He was ____ (terrible) hurt and had to stay in hospital for a long time.
⑻Many____ (wood) houses have been built for the tourists in this area recently.
⑼Mr. Brown ____ (prefer) hiking to running when he was in his twenties.
⑽Tian' anmen Square is always filled with ____ (visit) on National Day.