独山玉为（ ）光泽 A.
玻璃至油脂 B.
蜡状 C.
珍珠 D.
金刚

多项选择题栲胶浸提液蒸发时可采用哪些手段来提高蒸发强度？ A、合理地选用加热蒸汽和冷凝器的压力 B、及时排出冷凝水和不凝性气体 C、保持真空系统稳定 D、及时除垢

单项选择题How does Chris impress Twistle on the taxi in the film The Pursuit of Happyness?A. He finishes the magic cube which is very difficult for most people.B. He tells Twistle his experience in the past.C. He tells Twistle how much he likes this job.D. He tells Twistle that he is a single father and he has to support the family.