— Yes, she is my best friend Lucy. She is talented _________.
A:to sing
B:at singing
C:in singing
下列物质的用途,主要不是由其化学性质决定的是( )
如图,△ABC中,AB=AC,∠A=50°,P是△ABC内一点,且∠PBC=∠PCA,则∠BPC的度数等于( )