By and by means ‘after a short and/or undetermined period of time.’ Gradually refers to something happening in a gradual way; slowly; by degrees.

And is used to join words or groups of words. Also is defined as in addition.

'And' is used to join words or a group of words. Even is an adverb.

Above all - সর্বোপরি (more than anything else). Above and beyond - আরো বেশি (more than). Above board সংশয়হীন (beyond doubt), Above one’s station-কারোর সামাজিক অবস্থা থেকে উপরে

All in- ক্লান্ত (tired, exhausted); All in all- সর্বেসর্বা, সামগ্রিকভাবে (self-sufficient, overall); All in good time- নিকট ভবিষ্যতে (In the near future); All the same- একই (same); All the while- সারাক্ষণ (all the time)

As a matter of fact- বাস্তবে, প্রকৃতপক্ষে (in fact); As a result- ফলে (consequently); As a rule- সাধারণতঃ (generally); As far as- যতদূর পর্যন্ত (to the extent that); As long as- যতক্ষণ পর্যন্ত (until)