（ ）1. —What _______ cold weather!
—Yes. But it's ______ unusual experience for us who always live in a hot place.
A.an；an B./；a C./；an D.a；an
（ ）2. Alice could see her grandmother doing some cooking the kitchen’s glass door.
A. across B. through C. over D. against
（ ）3.— Has your sick pet dog been cured yet? — Not yet. It’s still under ________.
A. discussion B. control C. treatment D. repair
（ ）4. He made a serious mistake, but he took action to change that _________ it got worse.
A. until B. when C. because D. before