下列命题正确的是（ ）。
A. 若n阶行列式D=0，那么D中有两行元素相同
B. 若n阶行列式D=0，那么D中有两行元素对应成比例
C. 若n阶行列式D中有n²-n个元素为零，则D=0
D. 若n阶行列式D中有n²-n+1个元素为零，则D=0
In try to across a message,an EFL learner may use （ ）strategies to make up for a lack of knowledge of grammar or vocabulary.
A. communicative
B. cognitive
C. resourcing
D. affective
Which of the following writing activities may be used to develop student's skill of planning?
A. Editing their writing in groups.
B. Self-checking punctuations in their writing.
C. Sorting out ideas and putting them in order.
D. Cross-checking the language in their writing.
Which of the following is a typical feature of formal writing？
A. Archaic words are usually preferred.
B. The precision of language is a priority.
C. Short and incomplete sentences are preferred.
D. An intimate relation with the audience is established.