Abstract: In connection with a cover for preventing foreign matters, such as water, dirt, ice, snow and the like, from entering into an air intake duct of an internal combustion engine, which cover covers an opening of the air intake duct at a separation area of the air intake duct in an air-permeable manner, when the separation area of the air intake duct is open, the cover is operatively connected to a mechanism by which the cover is movable from its covering position, in which the opening of the air intake duct is covered, into a withdrawn position, in which the opening of the air intake duct is uncovered so that the air intake duct can be closed at the separation area, and vice versa.

Abstract: The hand-operated ratchet spanner contains a measuring value pick-up (4,9) for the angle of rotation of the screw and a device for measuring the torque. The measured values are supplied to a microprocessor (22) in which the screw tightening operation is preprogrammed by respective desired or limit values. Signal lamps (30,31,32) or acoustic signal transmitters (33) indicate to the user as to whether the screw has been correctly tightened. Further, he may recognize the extent to which the screw has been tightened and which part of the tightening operation must be still effected.

Abstract: Novel biologically active metabolites of vitamin D.sub.3, 1,23,25-trihydroxy-24-oxo-vitamin D.sub.3 (1,23,25(OH).sub.3 -24-oxo-D.sub.3); and 1,25,-Dihydroxy-24-oxo-vitamin D.sub.3 (1,25(OH).sub.2 -24-oxo-D.sub.3). Also the method of preparing these novel metabolites of vitamin D.sub.3. The use of these compounds in humans for the treatment of disease states involving calcium homeostatic disorders by the administration of an effective amount of said compounds.