【单选题】For a causal relationship to exist there must be evidence
A.
of an empirical correlation between the variables.
B.
that one variable precedes the other in time.
C.
that a third variable did not cause the changes observed in the first two variables.
D.
that one variable precedes the other in time and that the two variables are correlated.
E.
that one variable precedes the other in time, that the two variables are correlated and that this relationship is not spurious.
【单选题】Which environment variable must be changed in auser’s profile so that upon login,the command prompt identifies the server?()
【单选题】If average fixed costs equal $60 and average total costs equal $120 when output is 100, the total variable cost must be
【单选题】You need to retrieve the username cookie from an HTTP request. If this cookie does NOT exist, then the c variable will be null. Which code snippet must be used to retrieve this cookie object?
A.
Cookie c = request.getCookie("username");
B.
Cookie c = null; for ( Iterator i = request.getCookies(); i.hasNext(); ) { Cookie o = (Cookie) i.next(); if ( o.getName().equals("username") ) { c = o; break; } }
C.
Cookie c = null; for ( Enumeration e = request.getCookies(); e.hasMoreElements(); ) { Cookie o = (Cookie) e.nextElement(); if ( o.getName().equals("username") ) { c = o; break; } }
D.
Cookie c = null; Cookie[] cookies = request.getCookies(); for ( int i = 0; i < cookies.length; i++ ) { if ( cookies[i].getName().equals("username") ) { c=cookies[i]; break; } }
【单选题】Rose, who grows geraniums to sell, is currently producing a level of output at which her marginal cost equals her average variable cost. What must be true about Rose's average total cost at this level...
C.
It is falling with increased output.
D.
It is equal to average variable cost.
【简答题】 p____ a. 最重要的 n. 负责人,校长
【单选题】If a function needs to modify more than one variable, it must
C.
return all values needed
D.
be a call by reference function
【简答题】教学实施效果的评价的维度包括教学结构的转变、( )与( ) 。
【判断题】灰砂砖自生产之日起,应放置1个月以后,方可用于砌体的施工。