children are standing --- to get on the bus A.on line B.with

children are standing ___ to get on the bus A.on line B.with a line C.on a line .the children are standing ___ to get on the bus A.on line B.with a line C.on a line D.in line 2.I think the snow will make ___ difficult for us ___ the way back home A.that,to find B.it,to find C.that,find D.it,find 请注明原因