We should have a dream then try our best to achieve it.A. or B. but C. and

问题补充：

We should have a dream then try our best to achieve it.

A. or B. but C. and

答案：

解析：句意：我们应该有一个梦想，然后尽力实现它。and then adv.于是, 然后，根据句意，故选C。