Exercise: In the past three months, a new series of low-priced computers (has been released, have been released).

Discussion: Because the subject "series" is singular in this sentence, the correct verb is "has."

Exercise: The insurance company hopes that neither the architect nor the construction firm (are held, is held) liable.

Discussion: With a "neither/nor" construction of the subject, the number of the noun closest to the verb determines the number of the verb. In this case, because the noun "firm" is singular, the verb is singular.

Exercise: In the next section, the criteria for assessing each system (are given, is given).

Discussion: The noun "criteria" is plural.

Exercise: To connect a temperature measurement circuit to the HC11 microcontroller, we added new hardware and developed new software. The added hardware controlled both the measurement and the display of the temperature. This hardware (included, includes) light emitting diodes that (attach, attached) to Port B.

Discussion: In the first two sentences, the author has adopted a reference frame in which the circuit existed in the past. Therefore, for the rest of the document, that reference frame must be maintained. In reports that document the completion of a project, engineers and scientists usually adopt a reference frame that exists after the experiment or design has been disassembled. In progress reports, engineers and scientists usually adopt a reference frame in which the experiment or design still exists.

Exercise: To connect a temperature measurement circuit to the HC11 microcontroller, we added new hardware and developed new software. The added hardware controlled both the measurement and the display of the temperature. This hardware included light emitting diodes that (attach, attached) to Port B.

Discussion: In the first two sentences, the author has adopted a reference frame in which the circuit existed in the past. Therefore, for the rest of the document, that reference frame must be maintained. In reports that document the completion of a project, engineers and scientists usually adopt a reference frame that exists after the experiment or design has been disassembled. In progress reports, engineers and scientists usually adopt a reference frame in which the experiment or design still exists.

Exercise: To connect a temperature measurement circuit to the HC11 microcontroller, we added new hardware and developed new software. The added hardware controlled both the measurement and the display of the temperature. This hardware included light emitting diodes that attached to Port B. Figure 1 (showed, shows) a schematic of this hardware.

Discussion: Present tense is used here because the figure continues to show the readers a schematic of the hardware, even though the actual hardware has been disassembled. Such a use of present tense in the same paragraph that contains verbs in the past tense is not a tense error because the reference frame for the document remains constant.

Exercise: Conclusion. This report (has presented, presented, presents) a design of a temperature measurement circuit for the HC11 microcontroller.

Discussion: The present perfect tense is used here because most of the "presenting" has occurred in the past, but some "presenting" still remains. Note that in the "Introduction" of this report the tense choice for this sentence would be the present tense.