required in the library regulations that any book borrowed __________ by due time, or the borrower will be fined.

Have you ever seenbadweather

Once I am_________to carry out my plan, nothing can .

Yao Ming is practicing hard in Houston himself for the coming new NBA season. [ ]

When it ______ research into heart disease and its effects on the body, we do not have adequate substitutes for the use of animals.