Look at these two sentences:
Last century, patients with hearing impairment had to rely on behind-the-ear hearing aids. Now, with the advent of WiFi computer technology, and a cranial implant.."
Till now, patients with hearing impairment have had to rely on behind-the-ear hearing aids. The new WIFI computer technology revolutionizes the way...
Can you see what the difference is, in terms of 'time', between the two?
Student or Learner