向量a→=13,tanα,b→=cosα,1,且a→∥b→,则锐角α的余弦值为( )
《史记》记载,春秋时期有位国君为了报仇雪恨,“苦身焦思,置胆于坐,坐卧即仰胆,饮食亦尝胆也。”这位“国君”是( )
用元素符号或化学式填空.
(1)2个氢氧根离子____ ;(2)干冰____ ;
(3)硅元素____ ;(4)两个五氧化二磷分子 ____ .
根据材料,选择正确答案。
In Sunshine Town if you want to go to the cinema or theatre, look at the following first.
Sunshine Theatre (PLAYS ONLY)
Open: 11:30 a.m.-7:30 p.m. from Monday to Sunday
Ticket price: Member price:¥30 Usual price:¥40 Student:¥15
Telephone: 010-6697 3219
Sunshine Cinema
Open: 9:00 a.m.-8:00 p.m. Monday to Sunday
Ticket price:¥40 (half price on Tuesday)
Telephone: 010-6699 9977; 010-6699 6644
Sunshine Modern Cinema
Open: 10:30 a.m.-11:30 p.m. from Monday to Friday
10:00 a.m.-11:30 p.m. Saturday and Sunday
Ticket price: Adults:¥50 Children (under 14):¥10
The old (over 60):¥20 The young (15-18):¥20
Telephone: 010-6699 3834