请教几道逻辑题-->robert转移

1. It has been hypothesized that much of the matter in the university is “dark”, i.e., unseen. Studies have shown that galaxies in many galaxy clusters are moving faster with respect to one another than they would if visible stars constituted all their mass. The studies suggested that the galaxies are moving under the gravitational influence of unseen mass in considerable quantity.
Which of the following is an assumption underlying the passage above?
A) Measurements of the speed of moving galaxies are extremely unreliable
B) The workings of gravitational forces are not particularly well understood
C) The aggregate mass of visible stars in the galaxies mentioned above can be estimated with some confidence
D) The general composition of unseen matter in the universe has been determined
E) Without exception, the galaxies mentioned above move toward one another
2. Seven countries signed a treaty binding each of them to perform specified actions on a certain fixed date, with the actions if each conditional on simultaneous action taken by the other counties. Each country was also to notify the six other countries when it had completed its action.
The simultaneous-action provision of the treaty leaves open the possibility that
A) the compliance date was subject to postponement, according to the terms of the treaty
B) one of the countries might not be required to make any changes or take any steps in order to comply with the treaty, whereas all the other countries are so required
C) each country might have a well-founded excuse, based on the provision, for its own lack of compliance
D) the treaty specified that the signal for one of the countries to initiate action was notification by the other countries that they had completed action
E) there was ambiguity with respect to the date after which all actions contemplated in the treaty are to be complete
3. In respectable periodicals, books are given reviewing space in inverse proportion to the likely size of the their sales. Airport and supermarket bookstalls stock only books that are expected to sell in large numbers. Consequently, those who buy books at such bookstalls have to do so without any guidance whatever from the book reviewers whose work is published in respectable periodicals.
Which of the followings is a valid criticism of the argument above?
E)the conclusion that respectable periodicals never publish reviews of projected bestsellers is unwarranted
Why E is right?
4. Many geologists theorize that the trail of volcanic craters and cinder cones along the Snake River plain of southern Idaho was produced as the North American continent slid westward over a stationary” plume”, a veridical channel through which molten rock rose intermittently from the earth ‘s core to burst through its crust
D) the newest craters and cinder cones are on the eastern margin of the trail
Why D is right?