【单选题】“世外桃源该多好,无奈风波添烦恼,只缘矛盾来捉弄,它是庸人爱自扰。” 从哲学上看,此诗表达的观点错误在于( )
【简答题】放大电路中,晶体三极管的静态工作点设置得太高,会使 ic正半形和输出电压负半周进入 ___________区,造成 _________失真。
【单选题】下列说法中错误的是( ) ①化学性质相似的有机物是同系物 ②分子组成相差一个或几个CH 2 原子团的有机物是同系物 ③若烃中碳、氢元素的质量百分比相同,它必定是同系物 ④分子中含有碳、氢元素的化合物是烃类.
【单选题】Enquiry letters are often written _________ an advertisement that you have seen in the paper, magazine, or commercial on television.
【单选题】下列说法中正确的是①化学性质相似的有机物是同系物②分子组成相差一个或几个CH 2 原子团的有机物是同系物③若烃中碳、氢元素的质量分数相同,它们必定是同系物④互为同分异构体的两种有机物的物理性质有差别,但化学性质必定相似⑤分子式相同而结构不同的化合物互称为同分异构体
【单选题】I have four letters to write today and I have finished ______.
【单选题】You ______ all morning, but you ______ three letters!
A.
have been typing, have only done
C.
had been typing, have only done
D.
have typed, have only done
【单选题】I have four letters to write today and I have finished_________.