7.21 SC:OG 50 1.A 1972 agreement between Canada and the United...phosphates c n. 光气,磷酸盐(phosphate的复数形式)the amount of phosphates不要看到+s就联系到可数,时态交叉 2.Because there are provisions of the new maritime ...B, 3.Found throughout Central and South... C 4.Dressed as a man and using the name...D 5.Rising inventories, when unaccompanied...C 6.Paleontologists believe that fragments...A 7.Unlike the original National Museum...C 8.Buiding on civilizations that...D