My father has _______ a worker for ten years. [ ]
A. be
B. being
C. is
D. been
答案:D
下图为桃花结构示意图,其中能发育成桃子的结构是[ ]
下列能独立调味的基本味是()。
A、甜味
B、酸味
C、鲜味
D、辣味