—Why? I don't think they are useful.
A:take off
B:throw away
C:put into
D:bring in
烧杯中分别盛两种溶质不同的无色溶液,小木块上各有一支燃着的蜡烛,向甲烧杯撒入白色粉末X后,发现烧杯中蜡烛会熄灭,向乙烧杯中撒入黑色粉末Y后,则发现烧杯中蜡烛燃烧更旺.根据所学知识推测,X、Y分别是( )
“蜜蜂传粉”和“点水蜻蜓”这两种昆虫行为分别属于( )