国际频率登记委员会的缩写通常用（）表示。 A: WRC B: CCIR C: IFRB D: IFB

国际频率登记委员会的缩写通常用（）表示。 A: WRC B: CCIR C: IFRB D: IFB

1944年，54个国家在美国签署了芝加哥公约，随后在1947年，成立了（） A: IATA B: ICAO C: IFB D: ITC

下面不能看做一条语句的是（ ） A: {；} B: ifb==0） m=1;n=2; C: if(a>0); D: a=0,b=0,c=0;

When do people open up?: When they are comfortable|When they are sick|When they are uncomfortable|When they feel powerful

When people opening up? A: When they feel powerful B: When they are sick C: When they are uncomfortable D: When they are comfortable

When will an offer become effective? A: when it is dispatched B: when it reaches the offeree C: when it is withdrawn D: when it is revoked

Can you tell _______?: when did it happen|when it happened|when it was happened|when was it happened

When are multimedia tools effective? A: When they are colorful. B: When they enhance your message. C: When they involve technology. D: When they are funny.

When did the author take part in the race? A: When she was a freshman. B: When she was a sophomore. C: When she was a junior. D: When she was a senior.