When a spacecraft travels, one of the major problems is reentry into the Earth ’s _______.
A.surface
B.atmosphere
C.attitude
D.bent
A.surface
B.atmosphere
C.attitude
D.bent
第1题
A.burned; disappeared
B.burned; disappearing
C.burning; disappearing
D.burning; disappeared
第2题
第3题
A.Had there been
B.If there was
C.Were there to be
D.If there would have been
第9题
采用正逻辑的与门的真值表为( )。
A. <TABLE class=extable_c border=0 cellSpacing=0 align=center>
<TBODY>
<TR>
<TD>A B</TD>
<TD>Z</TD></TR>
<TR>
<TD rowSpan=4>0 0<BR>0 1<BR>1 0<BR>1 1</TD>
<TD rowSpan=4>0<BR>1<BR>0<BR>1</TD></TR>
<TR></TR>
<TR></TR>
<TR></TR></TBODY></TABLE>
B. <TABLE class=extable_c border=0 cellSpacing=0 align=center>
<TBODY>
<TR>
<TD>A B</TD>
<TD>Z</TD></TR>
<TR>
<TD rowSpan=4>0 0<BR>0 1<BR>1 0<BR>1 1</TD>
<TD rowSpan=4>1<BR>0<BR>1<BR>0</TD></TR>
<TR></TR>
<TR></TR>
<TR></TR></TBODY></TABLE>
C. <TABLE class=extable_c border=0 cellSpacing=0 align=center>
<TBODY>
<TR>
<TD>AB</TD>
<TD>Z</TD></TR>
<TR>
<TD rowSpan=4>0 0<BR>0 1<BR>1 0<BR>1 1</TD>
<TD rowSpan=4>0<BR>0<BR>0<BR>1</TD></TR>
<TR></TR>
<TR></TR>
<TR></TR></TBODY></TABLE>
D. <TABLE class=extable_c border=0 cellSpacing=0 align=center>
<TBODY>
<TR>
<TD>A B</TD>
<TD>Z</TD></TR>
<TR>
<TD rowSpan=4>0 0<BR>0 1<BR>1 0<BR>1 1</TD>
<TD rowSpan=4>1<BR>0<BR>0<BR>0</TD></TR>
<TR></TR>
<TR></TR>
<TR></TR></TBODY></TABLE>