有关as的用法

1. ______, the students continued their work.

A. Hardly as it was                                        B. Hard although it was 

C. Hard as it was                                          D. Though hard it was

2. ______, he is not afraid of it.

A. Hard as it is                                              B. As hard he is  

C. For it is hard                                            D. Because it is hard

3. ______, you will never succeed.

A. As you may try                                        B. How hard you try

  C. Try as you may                                       D. Try hard as you may

请问：应该选哪个？这个句式怎么用？