My father ____ in a panda protection center for 10 years, so he knows a lot about panda.( )
A.was workingB.is working
C.has workedD.will work
Yuan Longping is ___________ great scientist.He has helped to feed the world.
/
a
an
单词辨音。找出画线部分与其他单词发音不同的选项。
sk y
cit y
tid y
p ear
w ear
cl ear
h ouse
s oup
sh out
f ever
ch ess
sp end