A:43
B:xy
C:4
D:xy
若cosπ+α=-13,则cosα的值为( )
—Look at your hands, John. ______ of them is clean.—OK, I'll wash them at once.
看音节写词语
jué jì fó xìng bō li wǔ zhuāng
____ ____ ____ ____
wēi xiǎn zuān yán tài yáng
____ ____ ____
下列哪项不是自然科学研究的问题( )