高压电缆纸包换向的原则是什么？

如图所示，水平面内两根光滑的平行金属导轨，左端与电阻R相连接，匀强磁场B竖直向下分布在导轨所在的空间内，质量一定的金属棒垂直于导轨并与导轨接触良好．若对金属棒施加一个水平向右的外力F，使金属棒从a位置由静止开始向右做匀加速运动并依次通过位置b和c．若导轨与金属棒的电阻不计，a到b与b到c的距离相等，则下列关于金属棒在运动过程中的说法正确的（　　）

A．金属棒通过b、c两位置时，电阻R的电功率之比为1：2

B．金属棒通过b、c两位置时，外力F的大小之比为1：

C．在从a到b与从b到c的两个过程中，电阻R上产生的热量之比为1：1

D．在从a到b与从b到c的两个过程中，通过金属棒的横截面的电量之比为1：2

[说明]
已知一棵二叉树用二叉链表存储，t指向根结点，p指向树中任一结点。下列算法为输出从t到p之间路径上的结点。
[函数]
#define MaxSize 1000
typedef struct node
TelemType data;
struct node *lchild,*rchild;
BiNode, *BiTree;
void Path(BiTree t， BiNode *p)
BiTree *stack EMaxsize], *stack1 [maxsize], *q;
int tag[Maxsizel, top=0, top1;
q=t;
/*通过前序遍历发现P*/
do while (q!=NULL＆＆q! =p)
/*扫描左孩子，且相应的结点不为p*/
(1) ;
stack [top] =q;
tag [top] =0;
(2) ;

if (top＞0)
if (stack [top]==P) break; /*找到p，栈底到栈顶为t到p*/
if(tag[top]==1) top--;
else q=stack[top];
q=q-＞rchild;
tag [top] =1;


(3) ;
top--; top1=0;
while(top＞0)
q=stack [top]; /*反向打印准备*/
top1++;
(4) ;
top--;

while( (5) ) /*打印栈的内容*/
q=stack1[top1];
printf (q-＞data);
top1--;

以下关于RBS200和RBS2000的跳频方式，哪个是错误的？（）

A：用F-COMB的RBS200只能采用基带跳频方式。

B：用CDU-C的RBS2000，既可采用基带跳频，也可以采用射频跳频。

C：用CDU-D的RBS2000，既可采用基带跳频，也可以采用射频跳频。

D：用CDU-A的RBS2000，能采用射频跳频方式。

Millions of Americans and foreigners see GI.Joe as a mindless war toy, the symbol of American military adventurism, but that’ s not how it used to be. To the men and women who (1) in World War I1 and the people they liberated, the GI. was the (2) man grown into hero, the pool farm kid torn away from his home, the guy who (3) all the burdens of battle, who slept in cold foxholes, who went without the (4) of 1hod and shelter, who stuck it out and drove back the Nazi reign of murder. This was not a vohmteer soldier, not someone well paid, (5) an average guy, up (6) the best trained, best equipped, fiercest, most brutal enemies seen in centuries.

His name is not much. GI. is just a military abbreviation (7) Govermnent Issue, and it was on all of the article (8) to soldiers. And Joe A common name for a guy who never (9) it to the top. Joe Blow, Joe Magrae... a working class name.The United States has (10) had a president or vieepresident or secretary of state Joe.

GI. Joe had a (11) career fighting Geman, Japanese, and Korean troops. He appears as a character, or a (12) of American personalities, in the 1945 movie The Story of GL Joe, based on the last days of war correspondent Ernie Pyle. Some of the soldiers Pyle (13) portrayde themselves in the fihn. Pyle was famous for covering the (14) side of the warl, writing about the dirt-snow-and-mud soldiers, not how many miles were (15) or what towns were captured or liberated. His reports (16) the "willie" cartoons of famed Stars and Stripes artist Bill Maulden. Both men (17) the dirt and exhaustion of war, the (18) of civilization that the soldiers shared with each other and the civilians: coffee, tobacco, whiskey, shelter, sleep. (19) Egypt, France, and a dozen more countries, G. I. Joe was any American soldier, (20) the most important person in their lives.

16（）

A.paralleled

B.counteracted

C.duplicated

D.contradicted