We are supposed________our daughter's wedding.
A：to dress in
B：dressed up
C：to dress up for
D：be well dressed at
选词填空。
by am up are at is with in back come
在平行四边形ABCD中 向量AB→=a→，BD→=b→，试用向量a→，b→表示向量BC→，AC→．
已知⊙O1与⊙O2相切，⊙O1的半径为3cm，⊙O2的半径为2cm，则O1O2的长是（ ）
