如图,抛物线y=﹣x2﹣2x+3的图象与x轴交A、B两点,与y轴交于点C,点D为抛物线的顶点.
The light went off suddenly. Everything__________ very dark.
This is her book.________is on the table. ( )
人体肱三头肌受到刺激以后能收缩,它所受的刺激来自( )