丁烯-1产品组成中丁烯-1的设计含量是()。
A、≤99%
B、≤99.5%
C、≥99%
D、≥99.5%
参考答案:C
Do you think the skirt looks beautiful _____ me?[ ]
A. in
B. with
C. on
D. for
试述骨膜的构造和功能。