光纤分为多模光纤和单模光纤，下面的选项中，属于单模光纤的是（）。 A．8.3/125

根据短文内容，从下面方框中选择适当的单词或词组填空，使短文内容完整正确。（5小题*1=5分）

litter ; seldom ; Taking good care of ;  chopsticks ;   What’s more

I would like to introduce my best friend Tom to you. He is a very green person. He always goes out by bike or on foot,    小题1:  by car. He never uses disposable chopsticks. Whenever he eats out, he always takes his own     小题2:   with him. “Don’t litter” are his favourite words. When he sees others    小题3:   everywhere, he will help to clean it.    小题4: , he plants a tree on the hill near our school every year.
   小题5:  the planet is our duty. Let’s learn from him.