The main tasks of a computer programmer are first, to write programs to solve problems; second, to write them on time as they are needed; and third, to write them clearly by fully documenting them so that other programmers can understand them. The kinds of problems that are tackled(解决)depend on whether the programmer is working for a computer manufacturer or user. The former needs such programs as compilers, assemblers, executives, operating systems, and utility routines. These programs are intermediaries(中间者) between the machine and the commercial programs which are written in one of the high-level languages. They are about the system, and therefore programmers who write them are called system programmers. If the programmer is working for computer users, however, his or her programs may deal with either scientific or commercial problems.

Choose the best answer according to the passage

1) A computer programmer should undertake main tasks.
A. 1 B. 2 C. 3 D.4

2) The word they' in Line 2 of this paragraph refers to

A. programs B. programmers C. tasks D. problems

3) kinds of system programs are mentioned in the paragraph.
A. 5 B.6 C. less than 5 D. more than 6

4) is written in one of the high-level languages.
A. Machine B. System program

C. Intermediary D. Commercial program

5) Scientific or commercial programs are useful for

A. programmers B. computer users

C. manufacturers D. computers