Unfortunately, when I dropped in, Dr. Green ______, so we only had time for a few words.
A．just left B．has just left C．had just left D．was just leaving
The animal makes a strange sound, slightly ______ the bark of a dog.
A．resembling B．requesting C．resisting D．reflecting
You got back so late and you didn’t even give me a proper reason _______ you hadn’t called me! I’m very unhappy with you.
A．when B．why C．how D．which
There was a big dog ______ in front of Mr. Hill’s house, so David didn’t dare to go near it.
A．to sit B．sat C．sitting D．sits
The tourists can not help wondering ______ the ancient people could manage to complete the magnificent building without modern equipment.
A．that B．how C．where D．what
We have no choice. _______ we go or we stay, the result is the same.
A．Once B．Unless C．Whether D．While
