_____ the earth to be flat, many feared that Columbus would fall off the edge of the earth. [ ]

The new plan________three parts,each of which is very important.[ ]

People thought _____ hard to live without the medicine.

Tom ________ his father and his father________ young.

Roger had just walked into his office and that was when he was told that his plan had finally been approvedWhich of the following can be instead of the underlined(划线的) part to make the sentence better