1.in the 1950s =in the (middle ) of the ( twentieth) ( centry )
2.The sport of basketball has existed since a little over a hundred yearss ago.(对since从句提问即since a little over a hundred yearss ago)
Since when has the sport of basketball existed?
3The computer has influenced all walks of life.(翻译)
电脑已经影响了生活中的方方面面.
4.作为二十一世纪的学生,你们必须努力学习它并很好的掌握它、(翻译)
You should, as the students in the 21st centry, study hard and master it well.