Duty is an act or a course of action that peopleyou to take by social customs, law or religion.
| A． | persuade | B． | request | C． | instruct | D． | expect |
He told me that he had mailed part of the samples样本 and that the rest _____ in a few days.
| A．were following | B．have followed |
| C．has followed | D．was following |
He will give us a report on how to study English well, but when and where ________.
| A．is still unknown. | B．hasn’t decided |
| C．is known | D．haven’t been decided |
We should work together to build a society for kids, ________free from war and violence.
| A．one | B．this | C．it | D．that |
He slipped(溜进) into the classroom without ___________.
| A．noticed | B．noticing |
| C．being noticed | D．was noticed |
This special strain of rice makes _________ possible to produce one third more of the crop in the same fields.
| A．it | B．them | C．which | D．that |