Light travels at about ___. A.300,000 kilometres a secondB.a second 300,000 kilometresC.every second 300,000 kilometresD.300,000 kilometre every second
Light travels at about ___.
A.300,000 kilometres a second
B.a second 300,000 kilometres
C.every second 300,000 kilometres
D.300,000 kilometre every second
相关考题：
听力原文：M: So, Jane, how long have you been an author?W: Well, Tom, I didn't start writing until I was in my thirtieth, and I'm over seventy now. So goodness, I must have been writing for about forty years.How long has the woman been an author?A．About 30 years.B．About 40 years.C．About 60 years.D．About 70 years.
How many hours of housework did men do every week in the 1970s?A. About 23. B. About 26.C. About 13. D. About y.
How many hours of housework did men do every week in the 1970s?A．About 23.B．About 26.C．About 13.D．About y.
The word "diffuses" in Para. 3 is closest in meaning to ______.A) yieldsB) startsC) surfacesD) travels
阅读下列说明和C++代码，回答问题，将解答填入答题纸的对应栏内。【说明】某灯具厂商欲生产一个灯具遥控器，该遥控器具有7个可编程的插槽，每个插槽都有开关按钮，对应着一个不同的灯。利用该遥控器能够统一控制房间中该厂商所有品牌灯具的开关，现采用Command(命令)模式实现该遥控器的软件部分。Command模式的类图如下图所示。【C++代码】class Light {public: Light(stringname) { /* 代码省略 */ } void on() {/* 代码省略 */ } // 开灯 void off() {/* 代码省略 */ } // 关灯};class Command {public: （1） ;}；class LightOnCommand:public Command { // 开灯命令private: Light* light;public: LightOnCommand(Light* light) { this->light=light; } voidexecute() { （2） ; }};class LightOffCommand:public Command { // 关灯命令private: Light *light;public: LightOffCommand(Light* light) { this->light=light; } voidexecute() { （3） ; }};class RemoteControl{ // 遥控器private: Command*onCommands[7]; Command*offCommands[7];public: RemoteControl() { /* 代码省略*/ } voidsetCommand(int slot, Command* onCommand, Command* offCommand) { （4） =onCommand; （5） =offCommand; } voidonButtonWasPushed(int slot) { （6） ; } voidoffButtonWasPushed(int slot) { （7） ; }};int main() { RemoteControl* remoteControl=new RemoteControl(); Light*livingRoomLight=new Light("Living Room"); Light*kitchenLight=new Light("kitchen"); LightOnCommand*livingRoomLightOn=newLightOnCommand(livingRoomLight); LightOffCommand* livingRoomLightOff=newLightOffCommand(livingRoomLight); LightOnCommand*kitchenLightOn=new LightOnCommand(kitchenLight); LightOffCommand* kitchenLightOff=new LightOffCommand(kitchenLight); remoteControl->setCommand(0, livingRoomLightOn, livingRoomLightOff); remoteControl->setCommand(1,kitchenLightOn, kitchenLightOff); remoteControl->onButtonWasPushed(0); remoteControl->offButtonWasPushed(0); remoteControl->onButtonWasPushed(1); remoteControl->offButtonWasPushed(1); /* 其余代码省略 */ return 0;}
People are moving from major cities to smaller ones.A:big B:importantC:heavy D:light