1.Thegroundisriddledwithicewedges,manyquiteancient,caused(bythecoldearthcracks)andthecracksfilledwithwater.
A.bythecoldearthcracking
B.whenthecoldearthcracks.
括号内为啥选B不选A?and不是应该并列两个名词嘛?
2.Beesforageforfoodmanytimesaday,(theyareriskingbeingeaten)bypredators.
Aattheriskofbeingeaten
Briskingthemtobeeaten
是不是riskofdoingsth/attheriskofdoing才对?risktodo不对?