Officials from China and France formally promised on Thursday to build a new type of economic partnership, while ________ business cooperation.
A:strengthened
B:to strengthen
C:strengthening
D:strengthen
已知两个全等的直角三角形纸片ABC、DEF,如图(1)放置,点B、D重合,点F在BC上,AB与EF交于点G,
∠C=∠EFB=90°,∠E=∠ABC=30°,AB=DE=4.(1)求证:△EGB是等腰三角形(2)若纸片DEF不动,问△ABC绕点F逆时针旋转最小多少度时,四边形ACDE成为以ED为底的梯形(如图(2))求此梯形的高.
下列句中没语病的一项是 ( )
已知数列{an}的前n项和为Sn,且a1=1,an=2sn22sn-1n≥2则S2016=____
如图是桃花和桃果实的结构示意图,请据图回答问题: