So many natural disasters are believed___________over the recent years because of the frequent unreasonable mankind activities.
Several pages were found _________ when the book _________ me.
--- How many students are there in your school?--- There are 2,000 students here __________.
____________ two exams to worry about, I have to work really hard this weekend.
While shopping, people sometimes can't help ________ into buying something they don't really need.
The teacher bought many books for her students, which _____ 500.