Write three pairs of sentences using simple past and present perfect sa sleduyschimi dieslovo 1) us, 2) rait, 3) trevel

when i was leaving for school this morning, my friend called me.

1. in 1995 java was licensed by netscape for use in their internet browser, navigator. 2. basic has been extended by microsoft in its visual basic product. 3. perl was developed by lary wall in 1987. 4. specific problems are not solved by systems software. 5. in the last ten years, speed trap units have been installed by police on many busy roads.