1though——natural resources，the area is well developed.a.lacked b.lacking of c.lacking d.lacked in 答案【c】为什么不选b？2 my English teacher's humour was ________make every student burst into laughter.a.so as to b.such as to c.such th

1though——natural resources，the area is well developed.a.lacked b.lacking of c.lacking d.lacked in 答案【c】为什么不选b？2 my English teacher's humour was ________make every student burst into laughter.a.so as to b.such as to c.such th Res[z*cos(1/z),0]=? Res[sin z sin(1/z),0] Res[(e^z)-1)/z^3,0] 求留数 natural natural natural natural natural natural natural cats and dogs have always been natural——(敌人) 留数题,为什么Res[1/x,0]=1? Res[(z^2)/(z^2+1),i]求留数 求留数Res tanπz,z=1/2求留数Res tanπz,z=1/2 适当形式填空（说明原因）I like beautiful —(natural)very much.there are many — (natural)elements around us. though ——you don't know him,you can turn to him for helpA.even though B.though C.although D.As though为什么不能选B 这句话对么?——The Natural Disasters,May Be a Good Thing