With the help of high technology, many new substances（物质）______in the past years.
#102927
A
discovered
B
have discovered
C
had been discovered
D
have been discovered
推荐题目
John Wood，an Internet blogger，discovered that Samsung ________ for not protecting its workers from a dangerous chemical used on its phones.
#99762
A
had criticized
B
had been criticized
C
was criticized
D
was criticizing
Great changes in every field _____ in the last ten years.
#99202
A
take place
B
took place
C
have taken placed
D
had taken place
I don’t think Jim saw me ; he ______ into space .
#104041
A
just stared
B
was just staring
C
has just stared
D
had just stared
By the end of last month, ten primary schools _________ with the help of Project Hope.
#100770
A
had set up
B
had been set up
C
was set up
D
set up
— Have you heard about the recent election?— Sure, it ________ the only thing on the news for the last three days.
#100591
A
would be
B
is
C
has been
D
will be