______ the sound on the step, the boy rushed out to see if his mother had come back.
A．To hear B．Hearing C．Heard D．Hear
His answer was _______, so no one could make out what he meant.
A．ambiguous B．unconscious C．transparent D．explicit
_______ you don’t stay out too late, you may go to the party. But remember to be back here no later than 11:30 pm.
A．Now that B．Until C．Provided that D．Although
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
