1 . Look at the trouble we are in. If only we________(take)our teacher's advice. （所给词的适当形式填空）

2 . —Last year marks the 70th anniversary of the founding of People’s Republic of China. On October 1st, hundreds of thousands of people from all walks of life and around the country came to Beijing Tiananmen Square to witness this exciting moment.
—It’s a pity for me that I didn’t come. If only I ________ there with my family.

A．come

B．came

C．had come

D．have come

3 . —How impressive China’s 70th anniversary of National Day parade is!
—Definitely. If only I ________ on the scene!

A．was

B．were

C．have been

D．had been

4 . The upset mother thought to herself, “If only I ______ what’s going on in my little boy’s head right now.”

A．had known

B．know

C．knew

D．have known