Lest / in case (for fear that) / (by chance)
Lest / in case (for fear that) / (by chance)।
Lest —— should
In case ——- should
a) Sub1 + verb ——- + lest / in case + sub2 + should / might / would + verb’s base form + Ex
b) Sub1 + verb ——- + lest / in case + sub2 + verb-এর base form + Ex