Read the following sentence and Identify the function o...
单项选择题Read the following sentence and Identify the function of it in the introduction.
However, few have been reported on the precursor films generated bysputtering a CIG target. ()
A、Explaining the significance or necessity of the research
B、Reviewingthe existing literature relevant to the present study
C、Identifyinga gap in the existing literature
D、Announcing the purpose/focus ofthe study
E、Outlining the paper structure
