Cloning plants is straightforward while cloning animals is _____________ more complicated.

As it was almost time for the flight, all the passengers got ______ the plane.

. John hadn’t been able to quit smoking at once; he had to control his smoking desire      .

Most of the fans felt rather disappointed at the concert. They said it could have been _______ organized.

In our life, one question that ____ comes up is:“to be or not to be?”