n. an introduction to a book, especially one that explains the author's aims
A. refuge
B. pilot
C. pillar
D. preface
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vt. to keep a particular quality, feature, etc. ;to make sure that sth. is kept
A. reinforce
B. regulate
C. preserve
D. recover
to make a small hole in sth, or to go through sth. ,with a sharp object
A. progressive
B. penetrate
C. practical
D. pierce
a. of an appropriate size, amount or degree in comparison with sth.
A. primitive
B. proportional
C. preliminary
D. progressive
v. to make sb. feel less tired or less hot
A. pursue
B. refine
C. refresh
D. recollect