Time is so valuable that________ (Complete the sentence with suitable clause/phrase)

The poor man knocked at the door. He came to me with a view to  begging some food

Many illiterate people do not have any knowledge of health. If they were educated  They would not suffer from malnutrition

Scarcely had the teacher gone out of the room  when the students made much noise

My grandmother lives in a village. It is many years since  I met her

Trees are very important for our existence on earth. It is high time  we planted more trees/to plant more trees

Despite the fact that he worked very hard  he failed to complete the task. He was rather disappointed.