二维随机变量(X,Y)在D=（x，y）0<y<1-x2上服从均匀分布，求Z1,Z2联合分布。
Matteristhename________(give)toeverythingwhichhasweightandoccupiesspace.
Weregretto________thatitmaynotbepossibletodealwitheveryrequest.
Tostudyaforeignlanguage,__________.
Iwon't________thosechildrenmakinganoiseinmyhouse!
在点（0，-1）处的切线方程为 ________.
