In communication，a smile is usually ________ strong sign of a friendly and ________ open attitude. (2011·重庆，26)
| A．the；/ | B．a；an |
| C．a；/ | D．the；an |
He asked a lot of questions, and none of ______ was easy to answer.
| A．them | B．which | C．what | D．that |
He asked a lot of questions, none of ______ was easy to answer.
| A．which | B．them | C．what | D．that |
6. He had thousands of students, many of ______ gained great success in their own field.
| A．whom | B．them | C．which | D．who |
I met the fruit-pickers, several of _______ were still university students.
| A．that | B．who | C．them | D．whom |
Her sons, both of ______ work abroad, will come back home this summer.
| A．that | B．who | C．them | D．whom |