根据句意、释义或中文提示,写出句中所缺单词，使句子通顺。
（1）His parents are angry at his school work. They can't see his ____  (进步)after each exam.
（2）I don't know ____  ( if ) I will have time to join in some activities at school.
（3）Sometimes, I want to ____  (say that you will not do something) to do so much homework.
（4）Orange and yellow are warm colours, they can give you a happy and ____ (满意的) feeling.
（5）Peter is doing an ____  in the laboratory now.

一个长方形的长是10厘米、宽是4厘米，周长是（   ）