某二肽分子式为C5H10N2O3,其水解产物的R基有( )
A:﹣H
B:﹣CH3
C:﹣CH2CH2CH3
D:﹣CH2CH3
—Does Miss Yang speak English well? —Yes. She has no trouble the people from English-speaking countries.
Draw and match.将下列个图所缺身体部位不全完整,并连接。
____ ____ ____
A. leg B. ear C. eye
如图所示,在平行四边形ABCD中,对角线AC,BD相交于点O,下列条件不能判定平行四边形ABCD为矩形的是( )