重金属检查中,加入硫代乙酰胺时溶液控制最佳pH值为()
A. 2.5
B. 7.0
C. 3.5
D. 4.0
1. Whatisthepurposeofthispassage?
A.Toencouragemorepeopletousepublictransportation.
B. Tohelpyoumakeyourcommutebetter.
C.Toshowhowtostudyandcommuteatthesametime.
D.Toadvisereadersnottocommute.
2. Accordingtothepassage, whydopeoplespendmoretimecommutingto workandcollegenowadays?
A.Becauseit’sexpensiveforthemtorentapartmentsincities.
B.Becausecommutingisreallyrelaxingandfun.
C.Becausepublictransportationisverycheap.
D.Becausetheydon’thavetimetowalk.
3. Whydoesthepassagesuggestthatyoushouldtakethetrain?
A.It’scheaper.
B.It’slessstressful.
C.It’sfaster.
D. It’smorecomfortable.
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