已知某电厂发电机经220kV输电线路接于受端无限大系统母线，已归算到基准值的标么值参数如下(见图16-1)： 发电机输入系统的功率可按以下公式计算 式中 P—有功功率标么值； XΣ—系统的综合电抗标么值； δ—相量E与U之间的夹角(≤90°)。 静稳定理想功率极限（PM）计算时δ取（）。

A:80° B:90° C:85° D:75°

已知D点所在的6°带的高斯坐标值为：，则D点位于（）。

A:21°带，在中央子午线以东 B:36°带，在中央子午线以东 C:21°带，在中央子午线以西 D:36°带，在中央子午线以西

如右图所示，已知AB∥CD，点E在CD上，BC平分∠ABE，若∠C=25°，则∠ABE的度数是（）．

A:12.5° B:25° C:50° D:60°

Passage Five
Temperatures on December 12
City High Low
Cleveland .................. 37° 31°
Columbia, S. C ............ 60° 27°
Columbus, Ohio ............ 41° 34°
Dallas .................... 81° 50°
Dayton. ................... 41° 33°
Decatur ................... 39° 30°
Denver .................... 49° 33°
Des Moines ................ 34° 27°
Detroit ................... 37° 28°
Dubuque ................... 30° 23°
Duluth .................... 19° 10°
Eau Claire ................ 24° 19°
El Paso ................... 79° 36°
Evansville ................ 52° 36°
Fairbanks ................. -31° -40°
Fargo ..................... 17° -2°
Flint ..................... 31° 26°
Flagstaff ................. 56° 31°
Great Falls ............... 14° 3°
Grand Rapids .............. 33° 26°
Green Ray ................. 24° 20°

What was the high temperature in Columbus, Ohio on December 12（）

A:81°. B:50°. C:41°. D:60°.

Passage Five
Temperatures on December 12
City High Low
Cleveland .................. 37° 31°
Columbia, S. C ............ 60° 27°
Columbus, Ohio ............ 41° 34°
Dallas .................... 81° 50°
Dayton. ................... 41° 33°
Decatur ................... 39° 30°
Denver .................... 49° 33°
Des Moines ................ 34° 27°
Detroit ................... 37° 28°
Dubuque ................... 30° 23°
Duluth .................... 19° 10°
Eau Claire ................ 24° 19°
El Paso ................... 79° 36°
Evansville ................ 52° 36°
Fairbanks ................. -31° -40°
Fargo ..................... 17° -2°
Flint ..................... 31° 26°
Flagstaff ................. 56° 31°
Great Falls ............... 14° 3°
Grand Rapids .............. 33° 26°
Green Ray ................. 24° 20°

What was low temperature in Flagstaff on this day（）

A:26°. B:-2°. C:3°. D:31°.

Passage Five Temperatures on December 12 City High Low Cleveland .................. 37° 31° Columbia, S. C ............ 60° 27° Columbus, Ohio ............ 41° 34° Dallas .................... 81° 50° Dayton. ................... 41° 33° Decatur ................... 39° 30° Denver .................... 49° 33° Des Moines ................ 34° 27° Detroit ................... 37° 28° Dubuque ................... 30° 23° Duluth .................... 19° 10° Eau Claire ................ 24° 19° El Paso ................... 79° 36° Evansville ................ 52° 36° Fairbanks ................. -31° -40° Fargo ..................... 17° -2° Flint ..................... 31° 26° Flagstaff ................. 56° 31° Great Falls ............... 14° 3° Grand Rapids .............. 33° 26° Green Ray ................. 24° 20°

What was low temperature in Flagstaff on this day（）

A:26°. B:-2°. C:3°. D:31°.

Passage Five Temperatures on December 12 City High Low Cleveland .................. 37° 31° Columbia, S. C ............ 60° 27° Columbus, Ohio ............ 41° 34° Dallas .................... 81° 50° Dayton. ................... 41° 33° Decatur ................... 39° 30° Denver .................... 49° 33° Des Moines ................ 34° 27° Detroit ................... 37° 28° Dubuque ................... 30° 23° Duluth .................... 19° 10° Eau Claire ................ 24° 19° El Paso ................... 79° 36° Evansville ................ 52° 36° Fairbanks ................. -31° -40° Fargo ..................... 17° -2° Flint ..................... 31° 26° Flagstaff ................. 56° 31° Great Falls ............... 14° 3° Grand Rapids .............. 33° 26° Green Ray ................. 24° 20°

What was the high temperature in Columbus, Ohio on December 12（）

A:81°. B:50°. C:41°. D:60°.

如右图所示，已知AB∥CD，点E在CD上，BC平分∠ABE，若∠C=25°，则∠ABE的度数是（）．

A:12.5° B:25° C:50° D:60°