51.A

persistent

offender

惯犯

52.A

mingle

with

(使)与…混合

53.C

句子主干是：problem

is

acute

(问题严重)

54.C

(C选项的单词拼写错误，应该是subtract,意为“减、扣除”）

55.D

primitive

wooden

floors

原木地板

56.C

victims

遇难者\受害者

57.A

58.C

第二个单词不是indreased，而是increased....

strain在这里的意思是“

竭力使(某事物)超限”

59.C

gain

on

=to

gradually

get

closer

to

a

person,

car

etc

that

you

are

chasing

60.C