Sorry to interrupt you and Frank!

_________．We' re having a free talk．（　　）

A．Never mindB．Go ahead

C．I hope notD．That would be nice

I hear you've got an "A" in your English test． Congratulations!

____________．（　　）

A．It's a pleasureB．Take it easy

C．Many thanksD．You' re welcome

Do you think teenagers can't have a part﹣time job？

_____________．They may learn from working．（　　）

A．It's nothingB．Don't mention it

C．Hard to sayD．That's all right

Is Helen here？

Not yet， but she_________in half an hour．（　　）

A．arrivesB．will arrive

C．arrivedD．has arrived

In the past 70 years， China______historic changes and made great achievements．（　　）

A．experiencedB．has experienced

C．experiencesD．would experience