It is well understood _____ controls the flow of carbon dioxide in and out the atmosphere today.
| A．that | B．when | C．what | D．how |
He threw away all the ______ cigarettes, _______ to give up smoking for the sake of his health.
| A．remained; determining | B．leaving; determined |
| C．remaining; determined | D．left; determining |
Mandy, ___ university student from Canada, teaches us ___ history of western art.
| A．an; the | B．a; the | C．the; / | D．the; a |
He always works hard, but__________, he didn't pass the exam.
| A．much to our surprise | B．to our great surprising | C．to our surprise much | D．to surprise |
The book_______well.
| A．is sold | B．has been sold | C．selled | D．sells |
On _______ side of the river there are a lot of trees.
| A．both | B．any | C．either | D．neither |