Answer:

When a car is assembled out of its major components, is the order of assembly important?
- Yes—eg., the frame must be built before the wheels are put on it.
Can some of the major components be assembled independently?
- Yes—eg., the motor is built separately before being brought to the final assembly line.
Are some of the components made in separate factories?
- Yes—some in different countries.
Does the order of assembly matter for each component?
- Yes—each component is build of pieces that must be put together in order.
Does this sound an awful lot like putting together a big program?
- Yes.

Control Structures

In a program, a control structure determines the order in which statements are executed. You have already seen all the control structures any program will need:

Sequential Execution
Loops
Two-way Decisions

Sequential execution is when statements are executed one after another in order. You don't need to do anything special for this to happen. Loops are performed using the DO...LOOP control structure. Two-way decisions are performed using the IF...THEN...ELSE ...END IF structure.

These are the only control structures anybody needs, no matter what their task. Other control structures exist and are sometimes useful, but are never essential.

The basic control structures are like basic shop tools (hammer, saw, screw driver, ...). Most shop projects require the basic tools. Specialized tools might be helpful, but are not essential. You should learn how to use the basic tools before buying the specialized tools.

QUESTION 2:

Which of the following QBasic statements implements a control structure, and which are ordinary statements?

LET A = 5
DO...LOOP
SCREEN 12
PRINT "Hello"
IF...THEN...ELSE...END IF