四波混频是指（）后产生的新光波，为了抑制四波混频人们设计和制造出（）光纤。
参考答案：由两个或三个波长的光波混频，非零色散位移
根据句意，用括号中单词的适当形式填空。
小题1:—I want to study abroad but I’m afraid I won’t get used to the lifestyle there.
—It’s really a difficult __________ (decide) to make.
小题2:Miss Li has a strange way of making her class _________ (live) and interesting.
小题3: If you are _________ (honest), no one will make friends with you.
小题4:Some colourful activities are usually held in our school on __________ (woman) Day.
小题5:With everyone’s effort, Suqian is becoming ___________ (beautiful) than before.
新安装单绳缠绕提升机，其提升中心线位置偏差不超过（）mm。
A、20
B、15
C、10
