Our business won't improve ____ we offer better service to our customers．（ ）
A．becauseB．unlessC．afterD．since
We only planned the play for an hour，but in the end，we stayed for three hours．（ ）
| A． |
watch |
B． |
watches |
C． |
to watch |
D． |
watched |
Helping others makes us very ．（ ）
| A． |
lonely |
B． |
proud |
C． |
lazy |
D． |
harmful |
I in the city since I left school．（ ）
| A． |
live |
B． |
will live |
C． |
was living |
D． |
have lived |
The earth is a planet and it around the sun．（ ）
| A． |
goes |
B． |
go |
C． |
will go |
D． |
went |
Don't stand too close to North Americans．You'd better give them more personal ．（ ）
| A． |
time |
B． |
system |
C． |
space |
D． |
pity |