`1.` It is impossible for me to finish my work in twenty minutes.
`\text{It's impossible for sb to do sth = sb can't do sth}`
`2.` Unless you study hard, you won't pass the exam, you won't pass the exam.
`\text{Unless + S + V(s/es) + (O), S + will/won't + Vinf + (O). = If + S + don't/doesn't + Vinf + (O), s + will/won't + Vinf + (O).}`