Smoking is one of the ________causes of cancer，killing millions of people each year.
| A．major | B．similar | C．commercial | D．chemical |
He made a promisehe would not play computer games again at school.
| A．which | B．where | C．how | D．that |
Newly-developed materials for spaceships can _______ extreme weather conditions.
| A．hold | B．support | C．stand | D．compete |
The first prize goes to _______ makes the greatest contribution to our school.
| A．whomever | B．whichever | C．no matter who | D．whoever |
his homework, my son went downstairs to play basketball.
| A．Having finished | B．finished | C．to finish | D．finishing |
— Are you still thinking about the gift Tony gave you yesterday？
— Oh，to tell the truth, that’s makes me feel excited.
| A．what | B．how | C．that | D．why |