Bob called to tell his mother that he couldn’t enter the house, for he ________ his key at school.

A．had left           B．would leave        C．was leaving        D．has left

It’s a ________ clock, made of brass and dating from the nineteenth century.

A．charming French small                   B．French small charming

C．small French charming                   D．charming small French

The school board is made up of parents who ________ to make decisions about school affairs.

A．had been elected                       B．had elected

C．have been elected                      D．have elected

They promised to develop a software package by the end of this year, ________ they might have.

A．however difficult                       B．how difficult

C．whatever difficulty                      D．what difficulty

The judges gave no hint of what they thought, so I left the room really ________.

A．to be worried      B．to worry          C．having worried     D．worried

The students are looking forward to having an opportunity ________ society for real-life experience.

A．explore           B．to explore         C．exploring          D．explored

I have no idea ________ the cell phone isn’t working, so could you fix it for me?

A．what             B．why              C．if                D．which

Young people may risk ________ deaf if they are exposed to very loud music every day.

A．to go             B．to have gone       C．going             D．having gone

Sophia got an e-mail ________ her credit card account number.

A．asking for         B．ask for            C．asked for          D．having asked for

I cannot hear the professor clearly as there is too much noise ________ I am sitting.

A．before           B．until              C．unless            D．where