When the truth of sentence(a)guarantees the truth of sentence(b)and the falsity of sentence(b) guarantees the falsity of sentence(a)，we can say that_________．

[单选题]A sentence is considered when it conforms to the grammatical knowledge in t

[单选题]A sentence is considered when it conforms to the grammatical knowledge in t

[单选题]The last sentence of the text indicates the author’s______.［A］ hatred［B］ affection［C］ stubbornness［D］ rejection

[单选题]In the last sentence of the second paragraph, "the higher places on earth" refers to ______.A． the high mountainsB． the lighter rocksC． the vast oceanD． the great continent

[单选题]A．s used in the last sentence, the phrase "in short" means ______.A． in the long runB． in detailC． in factD． in a word

[主观题]Which sentence in the text is the closest in meaning to the following one?Teachers and students got friendlier so that the students became more active in learning and scored higher in tests.

[主观题]Translate the underlined sentence in Paragraph 3 Chinese.

[单选题]In the fifth sentence of the first paragraph, the word "pose" can be best replaced byA．bring aboutB．resultC．lead toD．offer

[单选题]B．y the first sentence of Excerpt 3 the author means that______.A．he is fairly familiar with the cost of advertisingB．everybody knows well that advertising is money consumingC．advertising costs money like everything elseD．it is worthwhile to spend mo

[单选题]In the first sentence of Paragraph 3,the word "cushion" can be best replaced byA．put a cushion underB．relieveC．eliminateD．avoid