I wish I ______ at my sister's wedding last Tuesday, but I was on a business trip in New York then.
A:will be
B:would be
C:have been
D:had been
—What were you doing when the earthquake happened in Jianhe ? —I morning exercises.
裸子植物与被子植物的相同之处是( )
如图所示,物体从O点由静止开始做匀加速直线运动,途经A,B,C三点,其中|AB|=2m,|BC|=3m.若物体通过AB和BC这两段位移的时间相等,则O,A两点之间的距离等于( )
某化工厂排放的废水中含有一定量的氢氧化钾,为了回收利用,欲用2%的稀盐酸测定废水中的氢氧化钾含量(废水中其他杂质不与盐酸反应),现取50g废水于锥形瓶中,逐滴加入2%的稀盐酸至恰好完全反应时,消耗稀盐酸7.3g,求废水中氢氧化钾的质量分数.