Reflexive Pronouns 5to 2

You are a good student, so you can do it by (a)   .

He is alone at home but, he is preparing food by (a)   .

Children are alone at home (no parents) but, they study hard by (a)   .

I don´t have internet but, I can do an investigation by (a)   .

I can prepare my breakfast, lunch and dinner by (a)   .

The puppy is happy because it eats meat, chicken and fish, all by (a)   .

We decided to study Frech and Italian, both by (a)   .

You (plural) need to work, study and pay the bills by (a)   .

Daniela is doing homework, all by (a)   .

Charly was angry because he did all the homework by (a)   .