ما الفرق بين ..............(الموضوع متجدد)

[omar30]

ما الفرق بين began to work
والثانية began working
لاحظ هذة الجملة من الكتاب المدرسي
1-هىIn the 1970, he began ( work – to work – works - working ) in an important heart hospital in Britain.
2-When he retired in 2001, he continued ( do – doing – does-to do) research
مع العلمأنها في الاجابة to do he continued