What is one of the difference between the use of single quotes and double quotes in PHP syntax?

Which statement will NOT combine strings $s1 and $s2 into a single string?

In this example code, $result = print_r ($a); $result is the

Given the following code, the Atom class can access which variables? class Flash { public $fast; private $superSpeed; private $ultraSonic; protected $warp; } class Atom extends Flash { }

Valid character for starting a PHP function name?

Atleast how many abstract methods must an abstract class contain?

Which code will return the IP address of the client?

DRY (Don't Repeat Yourself) is a principle of software development aimed at reducing repetition of software patterns. Which choice is not a way to write DRYer code with PHP?

Which superglobal variable holds information about headers, paths, and script locations?

What type of computer language is PHP?

Which is the most complete list of data types that PHP supports?