抛物线y=x2的焦点坐标为______.
∵抛物线y=x2,即 x2=y,
∴p=12,p2=14,
∴焦点坐标是 (0,-14),
故答案为:(0,-14).
Oh, much smoke here! Somebody ________ the window, please.
A.opens
B.open
C.shall open
D.will open
一般认为,早期显影是指显影剂引入体内后几小时以内的显影()
A.1h
B.2h
C.4h
D.6h
E.8h