1.  It (rain) for two days and the ground is too wet, so the match (be) postponed.

It HAS BEEN RAINING / HAS RAINED for two days and the ground is too wet, so the match HAS BEEN postponed.

2.  He (teach) many students but he never (meet) such a bad class as that.

He HAS TAUGHT many students but he HAS never MET such a bad class as that.

3.  A: What you (do)?
     B: We (pick) bananas.
     A: How many you (pick)?
     B: We (pick) ten baskets up to now.

A: What HAVE you BEEN DOING? B: We HAVE BEEN PICKING bananas. A: How many HAVE you PICKED? B: We HAVE PICKED ten baskets up to now.

4.  A: I (make) sandwiches for the party all the morning.
     B: How many you (make)?
     A: I (make) over 200.

A: I HAVE BEEN MAKING sandwiches for the party all the morning. B: How many HAVE you MADE? A: I HAVE MADE over 200.

5.  Diana (work) for them for over fifteen years and they never (increase) her salary.

Diana HAS BEEN WORKING / HAS WORKED for them for over fifteen years and they HAVE NEVER INCREASED her salary.