It is said that dogs will keep you ________for as long as you want when you are feeling lonely.
| A．security | B．friend | C．company | D．house |
Can you explain __________ the sun goes down in the west?
| A．why is it that | B．why it is that |
| C．how it is that | D．how is it that |
What an unforgettable experience ！ I'll write it down __________ it is still fresh in my memory.
| A．since | B．while |
| C．after | D．until |
__________，many people go in for them and benefit from them.
| A．However some sports are challenging |
| B．However challenging some sports are |
| C．No matter how challenging are some sports |
| D．No matter how some sports are challenging |
Although __________ to be the best in a recent science competition, the students remain hard-working.
| A．judged | B．judging |
| C．judge | D．having judged |
-You aren't looking well. Anything the matter?
-I've been surfing the net too long. I'm a bit tired. I can hold on，__________.
| A．though | B．yet |
| C．besides | D．therefore |