从A.B.C.D四个选项中，选出可以填入空白处的最佳选项。
1．--I am thinking of the test tomorrow. I am afraid I cannot pass this time.
--_________! I am sure you will make it.
A. Go ahead B. Good luck C. No problem D. Cheer up
2. People’s Republic of China is biggest developing country in the world.
A. the ;不填 B. 不填 ；the C. the ；the D. 不填；不填
3. If you have a job, ________ yourself to it and finally you will succeed.
A. do devote B. don’t devote C. devoting D. not devoting
