用所给动词的适当形式填空
3.Becarefulwithsuchthings.Ifyou________(notbe),you'lldropthem.
4.Theconstructionofthisbuildingstartedtwoyearsago,butit________(notcomplete)sofarduetovariousreasons.
5.Fortunately,thelittlegirl________(survive)theaircrash,butunluckily,theothersontheflightwerekilled.