That young man is honest，cooperative，always there when you need his help．______，he's reliable．（ ）
| A． |
Or else |
B． |
In short |
| C． |
By the way |
D． |
For one thing |
The national park has a large collection of wildlife, _________ from butterflies to elephants.
| A． |
ranging |
B． |
range |
C． |
to range |
D． |
ranged |
In the 1950s in the USA, most families had just one phone at home, and wireless phones _______ yet.
| A． |
haven't invented |
B． |
haven't been invented |
| C． |
hadn't invented |
D． |
hadn't been invented |
If you don't understand something, you may research, study, and talk to other people _______ you figure it out.
| A． |
because |
B． |
though |
C． |
until |
D． |
since |
Many airlines now allow passengers to print their boarding passes online ______ their valuable time.
| A． |
save |
B． |
saving |
| C． |
to save |
D． |
saved |
Jane moved aimlessly down the tree-lined street, not knowing ______she was heading.
| A． |
why |
B． |
where |
C． |
how |
D． |
when |