Why is marking up a book indispensable (21)_reading? First, it keeps you awake. (And I don,t mean
merely (22)_; I mean wide awake) In the second place, reading, (23)_it is active, is thinking, and thinking
tends to express (24)_in words spoken or written. The marked book is usually the (25)_book. Finally,
writing helps you remember the thoughts you had, or the thoughts the author expressed.
【題組】23. (A)if (B) even (C)however (D)though