We are very proud of these national________(英雄)．
She put back the book she had taken________mistake．
A．in
B．up
C．to
D．by
________it rains heavily，they go on working outside．
A．How
B．Why
C．Although
D．What
What________is the most helpful invention？
A．you think
B．I think
C．you do think
D．do you think
The dinner didn’t start________all the friends arrived．
A．since
B．until
C．while
D．by
He is________to lift the bag full of rice onto the truck．
A．enough strong
B．too strong
C．so strong
D．strong enough
