中国石油大学 / 中石油
正确率:100%
11. A new technique ______, the production increased by 20 percent.
A、to have been worked out
B、having worked out
C、working out
D、having been worked out
A、to have been worked out
B、having worked out
C、working out
D、having been worked out
参考答案:
佳题速递: