砷污染事件曾多次发生,含砷化合物一般都有毒性,其中以砒霜(As 2 O 3 )毒性最强,As 2 O 3 可用于制造杀虫剂和灭鼠剂等,是两性偏酸性氧化物,其无色晶体在193℃升华,微溶于水生成H 3 AsO 3 ;其对应的盐也有毒性。其中碱金属对应的盐易溶于水,其他金属对 应的盐几乎不溶于水。根据以上信息,下列说法正确的是
A.
As 2 O 3 是砷的最高价含氧酸的酸酐
B.
As 2 O 3 的晶体为原子晶体
C.
如不慎As 2 O 3 不慎撒落河水中,可投入纯碱以消除污染
D.
如不慎As 2 O 3 不慎撒落河水中,可投入生石灰以消除污染
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A.
recognition and confirmation: Excuse me, but are you/aren’t you …from …?
B.
greetings: Nice to meet you, Ms./Mr….
C.
self-introduction: I am …, your tour escort from …Travel Agency.
D.
more greetings: Welcome to China, Mr….How was your trip?
E.
Is everyone in the group here?
F.
Is that all your luggage?
G.
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