结晶为味精的氨基酸是（）
A.蛋氨酸钠
B.苏氨酸钠
C.亮氨酸钠
D.谷氨酸钠
E.缬氨酸钠
参考答案：D
在长方体ABCD─EFGH中，（1）哪些棱与棱AB平行？（2）哪些棱与棱AB相交？（3）哪些棱与棱AB异面？
He () the meeting, but upon learning that they would discuss something irrelevant to his field of study, he dropped the idea.
A. were going to attend
B. had attended
C. were to attend
D. would have attended
