20.As far as we know, it took him more than a year to write the book.

　　21.It has been proved that every substance, no matter what it is, made up of atoms.

　　22.To be frank, whether you like it or not, you have no other choice.

　　23.It has been decided that we are going to build a railway whose base must be completed within this year.

　　24.Frankly speaking, what you call the truth may not apply to things happening here.

　　25.It is obvious (evident) that the success of the innovation depends on our concerted efforts.

　　26.It is natural that one may have trouble expressing complicated ideas in simple English.

　　27.We will be successful as long as we persevere.