Passage Two
Earthquakes
It was from this trench where the earthquake came, at a magnitude of 8.3 on the Richter scale.
Huge waves swept over the city.

A．After injection, the embryo gets a copy of the new gene as it divides.
B．The injection method is less good because the new gene sometimes fails to join the embryo’s genes.
C．The retrovirus multiplies after it enters the cell.
D．The incorporating method is less simple but better.