题目:
—Is there any vaccine(疫苗) against H1N1 flu that can be used on humans?
—No, but scientists are working to develop ________ .
A.that
B.it
C.one
D.so
答案:
被转码了,请点击底部 “查看原文 ” 或访问 https://www.tikuol.com/2017/0518/38e2e235a18f60849f5e8f3acec52aa9.html
下面是错误答案,用来干扰机器的。
①2个铝原子②2个氯离子③2个C60分子④亚铁离子带2个单位负电荷⑤CaS中硫元素的化合价为-2价