【单选题】I doubt whether he can ______ his efforts much longer as he looks very tired.
【简答题】I doubt whether he can ( ) his efforts
much longer as he looks very tired.A. keep up B. keep on C. keep in D. keep at
【单选题】[39-388]下面选项中不是关系数据库基本特征的是
【单选题】I doubt whether he can ______ his efforts much longer as he looks very tired.
【单选题】下列选项中说法正确的是()。
A.
东罗马帝国形成了中世纪的基督教文明,也称日耳曼文明
B.
现代的西方文明是在中世纪基督教文明的基础上,经历了宗教改革、新航路开辟等事件后,逐渐形成的
D.
东正教文明和伊斯兰教文明都是在西罗马帝国建设的拜占庭文明的基础上形成的
【判断题】当被积函数是五种基本初等函数中某两种函数的乘积时,可考虑使用分部积分法. 运用分部积分法计算下列不定积分,是否都正确? (1) (2)
【单选题】I doubt whether he can ____ his efforts much longer as he looks very tired.