Q1:

=作用：赋值

==作用：判断数值相等但不判断类型

===作用：判断数值相等且判断类型

Q2:

switch ($X) {

case -2:

​    $p = 0.2;

​    break;

case -1:

​    $p = 0.1;

​    break;

case 0:

​    $p = 0.1;

​    break;

case 1:

​    $p = 0.3;

​    break;

case 2:

​    $p = 0.3;

​    break;

 

Q3:

If ($X == -2){

 

$p = 0.2;

} elseif ($X == -1){

$p = 0.1;

} elseif ($X == 0){

$p = 0.1;

} elseif ($X == 1){

$p = 0.3;

} else {

$p = 0.3;

 

}

Q4（言之合理即可）:

If ($xiaoming > $zhangsan){

echo ‘大于’;

} else {

小于

}