根据给出的汉语或者首字母写出正确的单词形式。

1．Mrs. Smith smiled ___________ (幸福)when she received the present on Mother’s Day．

2．The ___________ (高度)of the Mount Tai is about 1,532 meters．

3．Planting trees can help to make our _________ (环境)clearer and more beautiful．

4．The pandas live in the ______________(自然)reserve．

5．People learn languages to _________(沟通)with others．

6．The Chinese scientists did many scientific e______ before they sent the Chang’e-1(嫦娥一号) into space．

7．Everyone should stop p______ the Bailang River，instead of putting waste into it．

8．You must put the piano there，with its back a_______ the wall．

9．Li Hua fell off this bike this morning．Luckily，he didn’t hurt himself b__________．

10．He is my neighbor who lives u_______．But we are not familiar to each other， for he has never come down．

1、1．happily  2．height    3．environment  4．natural  5．communicate  6．Experiments

7．polluting  8．against  9．badly        10．upstairs