【简答题】已知a-b=1,ab=20,求a 2 +b 2 .
【简答题】在梯形面积公式S= 1 2 (a+b)h中,已知a=4,h=8. (1)若已知b=20,则面积S=______; (2)若已知S=20,求b的值.
【单选题】We don't know what ______ to her. [ ]
【简答题】I’ve been to Beijing.(翻译)
【单选题】已知a:b=c:d,若将b扩大20倍,使比例不成立的条件是( )
【单选题】(Either) the brother (or) the sister will tell (their) father about (what has happened).
【多选题】在未来国际战略格局多极化发展的进程中,起主导作用的国家是