21. Because of her illness, Helen has been absent from school for three days .
A. in a row B. in the row C. for a row D. over a row
22. In the early twentieth century, Australia the USA of the eighteenth century.
A. is resembled B. in resembling C. resembled D. resemblance
23. The twins are so alike that no one can one the other.
A. distinguish; from B. distinguish; between
C. distinguishes; from D. distinguishes; between