How many positive integers less than 20 are equal to the sum of a positive multiple of 3and a positive multiple of 4（）
A: Two
B: Five
C: Seven
D: Ten
E: Nineteen
A: Two
B: Five
C: Seven
D: Ten
E: Nineteen
举一反三
- The flux of electric field intensity E through a closed surface is equal to zero, which means in the surface A: there are more positive charges than negative charges. B: there are more negative charges than positive charges. C: there are the same quantity of the positive charges and negative charges. D: there is no polarized chargeharge.
- If 7l is an odd integer，then n2-1 must be（） A: a prime number B: an odd integer C: divisible by 8 D: a multiple of 2n E: a positive integer
- How long has the man worked in this company A: Five years. B: Less than two years. C: More than ten years.
- How to reply letter 3 A: positive B: negative
- Researchers found that it tended to be more _____ by analyzing word-of-mouth communication. A: negative than positive B: positive than negative