“______ can you stay here in the summer holidays?” “For two weeks.” 　　 [ ]

Amy 15 Yuan the comic book.

hat do you think of genetically modified food (转基因食品)? —We all think ______ is careless ______ some scientists to say it is safe before doing any experiment.

More than twenty_____students are having an important exam at the moment.

We all know that dinosaurs lived on the Earth more than ______ years ago.