在棉苗的3～4叶期，用精禾草克作茎叶喷雾处理棉花田内的（）效果很好。
A、阔叶杂草
B、单、双子叶杂草
C、双子叶杂草
D、单子叶杂草
参考答案：D
He was very angry when his car broke down, ________it serviced only a week before.[ ]
A. having had
B. having been had
C. to be had
D. having
女性，45岁，经常心前区疼痛，每次发作持续1小时以上，含服硝酸甘油半小时可以缓解，下列哪项诊断可能性大（）
A.急性心肌梗死
B.稳定型劳力性心绞痛
C.心脏神经官能症
D.心包炎
E.病毒性心肌炎
