A:避免长期接触潮湿空气
B:避免与酸性物质接触
C:不能接触干燥的空气
D:不能盛放硫酸铜溶液
下列元素的原子在形成不同物质时,既能形成离子键,又能形成共价键的是( )
用方框那所给的单词或短语完成下列各句,注意形式变化
(1) Where was your mother? --She ____ .(2) Let's____ school by bus.(3)The twins like ____ .(4)____ is fun for the twins.(5) I ____ I'm late.(6) Don't ____ school next time.(7)What ____ with you? I'm____ ill.(8)____ do you go to the park? Once a week.(9)Where ____ you ____ ? Canada.(10) Look! Liu Mei____ .