Beams of sunshine are waves of light and heat energy, radiated across 93 million miles of space to reach our earth in about ________.
A、a second
B、eight minutes
C、an hour
D、a year
A、a second
B、eight minutes
C、an hour
D、a year
A、carved beams and painted rafters
B、carved rafters and painted beams
C、a carved beam and painted rafter
D、N/A
A.frames
B.hull
C.stringers
D.plate
Laser beams can be used to bore metals and other hard materials.
A.trim
B.melt
C.drill
D.slice
If the sling bumps ______ the beams,serious accidents may follow.
A.at
B.on
C.into
D.against
A.short, perpendicular to
B.long, perpendicular to
C.short, parallel to
D.long, parallel to
Which of the following is not true?
A.Light waves are beams of light.
B.Light waves can penetrate any materials except men' s bodies.
C.Light waves can penetrate transparent materials.
D.Light waves can penetrate some materials.
Deck beams on a vessel are generally spaced at equal intervals and run ______.
A.longitudinally
B.vertically
C.transversely
D.intermittently
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