【题目】In schools, students________ to sweep the floor after school.

【题目】It's a custom in China to have some tea or other drinks before the meal ________.

【题目】In many schools, all the students ________ to show their student cards when they enter the library.

【题目】Many traffic accidents ________ because drivers use their smart phones while driving.

【题目】To make your DIY work perfect, you'd better not start ________ you get all the tools ready.

【题目】A true friend can see the pain in your eyes ________ everyone else believes the smile on your face.

【题目】I was giving a phone call to my mum________ Jim asked me for help.

【题目】She is listening to music ________ Peter is doing his homework.

【题目】Chen Wei isn't at school today________ he is taking part in a robot competition in Shanghai.

【题目】Studying in groups is necessary _________________ you want to do well in school.