Complete the sentences with the given words in their proper forms（用括号中所给单词的适当形式完成下列句子）
【小题1】The students promise to__________ (helpful) them to protect the environment.
【小题2】PM 2. 5 shows us how heavy the air__________ (pollute) there is.
【小题3】Samuel is going to share ___________ (he) food with Alice.
【小题4】How many___________ (uncle) do you have, Joe?
【小题5】Joyce is always kind to us. She never gets ___________ (angrily).
【小题6】Kitty's father is visiting the U. S. A for the ___________ (two) time.