Jack _______ yet last night, otherwise he _______ me.
   A. mustn’t have arrived; must have phoned   B. can’t have arrived; would have phoned
Between the two parts of the concert is an interval, ___ the audience can buy ice-cream.
| A.when | 
| B.where | 
| C.that | 
| D.which | 
___ from other continents for millions of years, Australia has many plants and animals not found in any other country in the world.
| A.Being separated | 
| B.Having separated | 
| C.Having been separated | 
| D.To be separated | 
When ___ help, one often says”Thank you” or”It is very kind of you”.
| A.offering | 
| B.to offer | 
| C.to be offered | 
| D.offered | 
The villager acting as our ___, we enjoyed our visit very much
| A.helper | 
| B.assistant | 
| C.leader | 
| D.guide | 
Only if you are ___ about your future, you can achieve your aim.So, don’t lose heart but cheer up.
| A.worried | 
| B.curious | 
| C.eager | 
| D.optimistic |