His illness ________ his absence．So don’t scold him．
| A．showed | B．accounts for | C．explains | D．gives out |
I regret ___ harder in the past two years.
| A．not having studied | B．having studied | C．having not studied | D．not being studied |
Had your father seen the doctor earlier, he ___.
| A．would have died | B．would not have died | C．would not die | D．has not died |
Tom’s uncle must be an engineer, ___?
| A．mustn’t he | B．can’t he | C．isn’t he | D．needn’t he |
He ___ on the grass, looking at the clouds in the sky.
| A．is laying | B．is lying | C．has laid | D．has lied |
His mother ___ a lot of silkworms last summer.
| A．rose | B．fed | C．raised | D．grew |