Look! Serveal __ are watching a group of ___ eating grass on the hill.

One of the consequences of our planet's being warming up is a（n）_______ in the number of natural disasters. 

.Having heard the customers’ ________, they decided to improve their products.

 She raised her finger to her lips as _________ for silence. 

There might be life on other planets, but so far scientists haven't found enough ________ to prove it.