We should do what we can _____ theendangered animals.`–Yes, it’s duty_____ them.

study is hard work, we’d bettercontinue to the end.

There are so many delicious food in the menu.I can’t decide ________.

“When did he leave the classroom?” “He left _______ you turned back to write on the blackboard.”

There was _____ between the police and the public in catching the criminal.