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