Why can redwoods survive so long？A．The optimum climate.B．Absence of natural enemies.C．Coas

According to the passage, why so many family－run businesses fail to survive？A．Because they

The thought of dying slowly and painfully （)me. I really can t understand why so man

According to Darwin, why do people laugh？A．Laugh is a survival technique for babies.B．They

Why do many tourists visit Muirwoods rather than other redwoods forests？A．It has admission

They must have been enjoying themselves there, or they______so long.A．can"t have stayedB．w

Why is a long piece of string tied tightly round the neck of each bird？A．Because it can pr