By the middle of the 21st century , the vast majority of the world’s population ________ in cities rather than in the country.
| A．are living | B．will be living |
| C．have lived | D．will have lived |
I thought it a pity __________ him to the tea party.
| A．being not invited | B．not to have invited |
| C．to not have invited | D．not to have been invited |
.A reward of 1,000 dollars will be given ________ can find the lost child.
| A．whomever | B．whoever that | C．to whomever | D．to whoever |
.So often ______ in recent years that it has almost become a rule.
| A．has this happened | B．this has happened |
| C．is this happening | D．for this to happen |
.The farmer who admitted ______ the tiger was severely punished.
| A．to kill | B．killing | C．killed | D．to have killed |
.They ______ be at home. You see, the door is locked from the outside.
| A．can’t | B．may | C． must | D． mustn’t |