—Kathy and her sister are so alike.—I can’t tell one from ____.
The crazy fans___________ patiently for two hours, and they will wait till the movie star arrives.
When ____ to danger and conflict, men tend to increase blood pressure, ____ nervous or anxious.
It is believed that _____ European scientist invented _______.
I don’t think David could have done such a stupid thing last night, ____?
We had tried everything to improve their living conditions,but it made little .