OG11 69 70 关于平行省略

69. A report by the American Academy for the Advancement of Science has concluded that much of the currently
            uncontrolled dioxins to which North Americans are
            exposed comes from the incineration of wastes.

(A)      much of the currently uncontrolled dioxins to which North Americans are exposed comes

(B)      much of the currently uncontrolled dioxins that North Americans are exposed to come

(C)      much of the dioxins that are currently uncontrolled and that North Americans are exposed to comes

(D)      many of the dioxins that are currently uncontrolled and North Americans are exposed to come

(E)      many of the currently uncontrolled dioxins to which North Americans are exposed come

OG说to maintain the parallel, that would have to be repeated in the clause that North
                    Americans are exposed to
            排除D
                这里的平行里，that一定要重复的原因是不是和and离太远了？但是请看下面这题

(A)      to affect the trajectories of ballistic missiles, induce

(B)      that the trajectories of ballistic missiles are affected, induce

(C)      that it affects the trajectories of ballistic missiles, induces

(D)      that the trajectories of ballistic missiles are affected and induces

(E)      to affect the trajectories of ballistic missiles and induce

OG说   It heats the atmosphere enough to affect
                            x and (to) induce y; the preposition to does not need to be repeated because it is understood.
                    为什么这里and后面的to就可以省略，上面的that确不行？

Despite protests from some waste-disposal companies, state health officials have ordered
            the levels of bacteria in seawater at popular beaches to be measured and that the results be
        published

(E)  that the levels of bacteria in seawater at popular beaches be measured and the results

答案是 E，为什么这里的that可以省略呢，一直搞不懂什么时候可以省略 that 什么时候不可以？