A:原子半径:r(W)>r(Z)>r(Y)>r(X)
B:Y的简单气态氢化物的热稳定性比Z的强
C:由X、Z组成的化合物与由Z、W组成的化合物只能发生化合反应
D:由X、Y、Z三种元素组成的化合物可以是酸、碱或盐
The woman came to see John yesterday is his aunt.
把下面的分数填在合适的圈里.(按试题中的顺序,先填真分数,后填假分数,填写分数时,先填分子,后填分母)
52 , 38 , 1010 , 139 , 63 , 27100 , 411
如果|a+2|+(b﹣1)2=0,那么(a+b)2013的值是( )
用方框内所给单词或短语的适当形式填空
(1) Could you ____ me ____ my lessons this evening, please?(2)____ May Lee ____ from school the day before yesterday?(3) The children____ in the park now.(4) It’s time____ . Let's begin.(5) Can you____ your picture to me?(6)____ taking a walk after supper ____ your health? --I think so.(7) Do you enjoy ____ vegetables?(8) Open your books and ____ to Page 50, please.(9) Could I ____ your bike, please, please? Mine is broken.(10) It's very cold outside. You must ____ your overcoat.
(2015•济宁)若1×22﹣2×32=﹣1×2×7;
(1×22﹣2×32)+(3×42﹣4×52)=﹣2×3×11;
(1×22﹣2×32)+(3×42﹣4×52)+(5×62﹣6×72)=﹣3×4×15;
则(1×22﹣2×32)+(3×42﹣4×52)+…+(2n﹣1)(2n)2﹣2n(2n+1)2=____