19 . ____ a reply , he decided to write again .
A . Not receiving B . Receiving not
C . Not having received D . Having not received
20 . “Can\'t you read ? ”Mary said ____ to the notice .
A . angrily pointing B . and point angrily
C . angrily pointed D . and angrily pointing
21 . more attention , the trees could have grown better .
A. Given B. To give C. Giving D. Having given
22 . The computer centre , ____ last year , is very popular among the students in this school .
A . open B . opening C . having opened D . opened
23 . Charles Babbage is generally considered ____ the first computer .
A . to invent B . inventing C . to have invented D . having invented
24 .— I must apologize for ____ ahead of time .
— That\'s all right .
A . letting you not know B . not letting you know
C . letting you know not D . letting not you know
25 . Rather than ____ on a crowded bus , he always prefers ____ a bicycle .
A . ride ; ride B . riding ; ride C . ride ; to ride D . to ride ; riding
26 . The missing boys were last seen ____ near the river .
A . playing B . to be playing C . play D . to play
27 . The visiting minister expressed his satisfaction with the talks , ____ that he had enjoyed his stay here .
A . having added B . to add C . adding D . added
28 . The first textbooks ____ for teaching English as a foreign language came out in the 16th century .
A . having written B . to be written C . being written D . written
29 . Paul doesn\'t have to be made ____ . He always works hard .
A . learn B . to learn C . learned D . learning
30 . We agreed ____ here but so far she hasn\'t turned up yet .
A . having met B . meeting C . to meet D . to have met
31 . — You were brave enough to raise objections at the meeting .
— Well , now I regret ____ that .
A . to do B . to be doing C . to have done D . having done
32 . — I\'ll be away on a business trip . Would you mind looking after my cat ?
— Not at all . ____ .
A . I\'ve no time B . I\'d rather not C . I\'ll like it D . I\'d be happy to
33 . The boy wanted to ride his bicycle in the street , but his mother told him ____ .
A . not to B . not to do C . not do it D . do not to
34 . The patient was warned ____ oily food after the operation .
A . to eat not B . eating not C . not to eat D . not eating
35 . It is wise to have some money ____ for old age .
A . put away B . kept up C . given away D . sep up
36 . ____ in thought , he almost ran into the car in front of him .
A . Losing B . Having lose C . Lost D . To lose
37 . She is upstairs letters .
A. writes B. is writing C. write D. writing
38 . The speaker raised his voice but still couldn\'t make himself .
A. hear B. to hear C. hearing D. heard
39 . — Alice , why didn\'t you come yesterday ?