Students here often do physics experiments _____small groups．（ ）
A．byB．inC．forD．at
Great changes have taken place in Tongliao City．
Yes，our city is______________ than before．（ ）
| A． |
beautiful |
B． |
much beautiful |
| C． |
much more beautiful |
D． |
most beautiful |
I called you at eight o'clock last night，but nobody answered．
Oh，I________ a shower at that time．（ ）
| A． |
am taking |
B． |
took |
C． |
is taking |
D． |
was taking |
The policeman warned us________ the busy street when the traffic lights are red．（ ）
| A． |
don't cross |
B． |
not crossing |
| C． |
not to cross |
D． |
can't cross |
The doctor was busy ______on the woman at that time．（ ）
| A． |
operate |
B． |
operating |
C． |
to operate |
D． |
operated |
My necklace is not the only thing is missing．（ ）
| A． |
/ |
B． |
which |
C． |
who |
D． |
that |