There's no way of knowing why one man makes an important discovery________another man，also intelligent，fails.
| A．since | B．if | C．as | D．while |
For the kite-flying competition, his grandfather made a _____ kite．
| A．silk dragon-shaped golden | B．golden silk dragon-shaped |
| C．dragon-shaped golden silk | D．golden dragon-shaped silk |
— My sons are not a little restless．
— Oh? Boys _______ be boys．
| A．should | B．can | C．may | D．will |
— Why didn’t you give a hand to the boy?
— I _______, but he struggled to his feet before I tried to．
| A．would like to have | B．would like to |
| C．would rather to have | D．would better |
—You didn’t invite Mary to the ball?
—____ her, too?
| A．Must I invite | B．Should I have invited |
| C．Must I have invited | D．Should I invite |
I only know we will have a League meeting, but I have no idea when _________ it．
| A．shall we have | B．will we have | C．to have | D．having |