— Can you explain ____ you have been late for school several times this term?— Sorry, but it is the first time that I have been late this week.
Some hard working students always keep a torch in their dormitories _____ there is a power failure.
_____ in charge of two classes made Mrs.Li, head of Senior Grade 3, extremely tired.
Almost every teenager will experience a period in their life _____ they aren’t content with their parents.
Little did the teacher imagine that a student good at maths _____ have failed in the exam.
— I’ve never seen you so rude! — I _____ something I shouldn’t have, but I didn’t mean that.