1.he didn't speak to me,let alone__me.A.help B.to help c.helping d.helped 2.once __ ,a bad habit is rather difficult to get rid of.a.formed b.to be formed c.forming d.having formed 3.__not knowing the answer to such an easy question A.hope B.decide C.imagine D.think 5.it ___ this way A.used to do B.used to be done C is used to doing D.is using to do 6.when___,water can be changed into vapor A.heated B.being heated C.having been heated D.to heat