低沸塔液位波动的原因是（）
A、塔釡热水阀门过大
B、全凝器下料不畅，平衡管结冰
C、尾气放空量过大
D、尾气放空量过小
参考答案：A, B, C
用所给单词的适当形式填空。
l. It's important for us _______ (exercise) very often.
2. I hope you're _______ (enjoy) my school.
3. I'm feeling much ______ (good) now.
4. ______ (eat) healthy food is good for us.
5. ______ (not eat) junk food.
评定吞入食物逆流属于（）。
A.摄食过程的先行期
B.摄食过程的准备期
C.摄食过程的口腔期
D.摄食过程的咽部期
E.摄食过程的食管期
