APEX TOEFL GRAMMER UNIT 4
16.It is only in recent years that people have become aware -------- a clean environment means to us human beings
(A)that
(B)of that
(C)of what
(D) of which
(A:C
17.The formation of the universe can be explained by ------------ the "Big Bang" theory
(A)what scientists call
(B)that scientists call
(C)scientists call what
(D)which is called
(A:A
19.In 1857, Elizabeth Blackwell established the first hospital for women and children, which later became-----------is now the New York Infirmary for Women and Children
(A)what
(B)that
(C)where
(D)when
(A:A
