— _________, this math problem seemed quite simple to me, but when I tried to work it out, I just couldn’t.

— There are always things like this, I think.

A．On one hand

B．In my opinion

C．At first sight

D．On its own

在中国革命、建设和改革问题上，我们要坚持把马克思主义同我国实际结合起来，坚定不移地走自己的路。