【单选题】某元素的质量数为23,中子数为12,该元素的核电荷数为( )
【单选题】The single sentence that summarizes a speaker’s central message in a presentation is called the _________ statement.
【简答题】证明若xs(t)(s=1,2,…,m)分别是方程 设x1(t),x2(t)是二阶线性微分方程 对应的齐次方程的两个设x1(t),x2(t)是二阶线性微分方程 对应的齐次方程的两个线性无关的特解,其中a1(t)和a2(t)是区间α≤t≤β上的连续函数,证明所给方程在区间α≤t≤β上的通解为 其中c1,c2为任意常数.
【单选题】According to the passage, what can we infer to be the central message of Fredric Wertham's The Seduction of the Innocent?
A.
Adults reading violent comic books were as likely to be corrupted by them as young people were.
B.
The horror comic books of the late 1940s were inferior to the superhero comic books that gained popularity during World War Ⅱ.
C.
Comic books were leading the nation's youth into crime, violence, and drug abuse.
D.
Creating a regulatory board to censor the comic book industry would drive the worst offenders out of the business.
E.
Comic books would never be able to convey stories of any serious literary merit.
【判断题】The main idea is the central theme or the most important thought of a message.
【判断题】The main idea is the central theme or the most important thought of a message.