_____ it will do us harm or good remains to be seen.
| A．If | B．Whether | C．That | D．What |
The teachers are doing what they _____ their stuaits.
| A．can to teach | B．can teach | C．can teaching | D．can to teaching |
They were _____ inventors than pure scientists.
| A．more | B．less | C．many | D．worse |
Old as the car is, _____ it works quite well.
| A．but | B．yet | C．so | D．however |
The stubborn boy didn't _____ so that he missed the chance.
| A．take advice | B．follow an advice | C．give some advice | D．ask for advice |
You'd better make a mark _____ you have any questions.
| A．at which | B．at where | C．the place | D．where |