According to Charles Keeling, the amount of carbon dioxide ________ sharply and steadily over the forty years between 1957 and 1997.
| A．increased | B．had increased |
| C．had been increased | D．was increasing |
It was along the Mississippi River _______ Mark Twain spent much of his childhood.
| A．how | B．which | C．that | D．where |
It was not until midnight __ they reached the camp site.
| A．that | B．when | C．while | D．as |
It was in New Zealand ___ Elizabeth first met Mr. Smith.
| A．that | B．how | C．which | D．when |
----Where did you get to know her?
------It was on the farm ____we worked.
| A．that | B．there | C．which | D．where |
I do not mind her criticizing me, but _____ is how she does it that I object to.
| A．it | B．that | C．this | D．which |