如果我们不能正视异性同学的关系，认为异性同学间不会有正常的交往和真正的友谊，就会导致我们[ ]

①对男女同学的交往过于敏感、拘禁

②产生性别意识，过早地成熟

③害怕与异性同学进行正常的交往

④把异性同学间的交往看成是学校生活的一个重要内容

A．①②

B．③④

C．①③

D．①②④

  So difficult __________ it to work out the problem that I decided to ask Tom for advice.

A．I did find

B．did I find

C．I have found

D．have I found