These light bulbs look the same，but their ______ on the environment are different．（ ）
| A． |
solutions |
B． |
methods |
C． |
effects |
D． |
secrets |
It's sports time．Most ________ students in Class 1are playing football on the playground．（ ）
| A． |
boy |
B． |
boys |
C． |
boy's |
D． |
boys' |
You should ask Bob ______ his own clothes．He is ten years old now．（ ）
| A． |
wash |
B． |
washes |
C． |
washing |
D． |
to wash |
It's hot today．Have some ______ please．
No，thanks．I'm not thirsty at all．（ ）
| A． |
water |
B． |
potatoes |
C． |
bread |
D． |
cakes |
I ______ the History Museum twice．I've learned a lot there．（ ）
| A． |
visit |
B． |
am visiting |
| C． |
have visited |
D． |
will visit |
Do you like watching ping﹣pong matches？
Yes，and ________ favorite ping﹣pong player is Ma Long．（ ）
| A． |
we |
B． |
us |
C． |
our |
D． |
ours |