A:when was it that
B:that it was whe
C:where it was that
D:it was where that
—Sorry, sir. I wasn't there at that time yesterday.
- There are so many friends at your birthday party. -Yes. And I hope Mr. Li_______ too.
设点F1,F2分别是椭圆C:x2a2+y2b2=1a>b>0的左、右焦点,P为椭圆C上任意一点,且PF1→·PF2→的最小值为0,则椭圆的离心率为( )
共价键、离子键、分子间作用力都是微粒间的作用力,下列物质中含有以上两种作用力的晶体是( )
下面每句话中均有一处语病,请找出来并修改。
①创建全国文明城市不仅能够提升市民精神生活的品位,而且可以进一步完善城市基拙设施。②在全国文明城市创建活动中,全市人民参与程度的高低和创建力度的大小是成功的关键。③我们要树立“虞城是我家,文明靠大家”的观念,以高度的责任感、积极的主人翁姿态参与投身到创建活动中去。