Which of the following conditions is true concerning a flammable liquid with a concentration above the upper explosive limit?

A．The mixture is too lean to burn

B．The mixture is too rich to burn

C．The vapor is about to explode

D．Conditions are perfect for combustion

[单选题]Which of the following conditions will make a relation that is in first normal form. to be in second normal form?Ⅰ.every non-key attribute is functionally dependent on the full set of primary key attributes.Ⅱ.no non-key attributes exist in the relati

[单选题]Which of the following conditions is realized by the turbo-charging of a previously naturally aspirated diesel engine?A．Ignition lag increases.B．Lube oil system pressure increases.C．Brake specific fuel consumption increases.D．Mechanical efficiency in

[单选题]Which of the following conditions could contribute to the cracking of a diesel engine cylinder head?A．Leaking seal ringB．Insufficient heat transfer from the exhaust valvesC．Blocked cooling water passages to the headD．Excessive scavenging air provided

[单选题]Which of the following conditions could cause the feed pump for an auxiliary boiler to lose suction?（）A . Increased suction head pressureB . Decreased feedwater temperatureC . Pump recirculating line being open too muchD . Excessive feedwater tempera

[单选题]Which of the following statements is TRUE according to the reading passage?A． Parents should be more tolerable towards their children.B． The younger generation should value the older generation for their wisdom.C． The generation gap is partly created

[单选题]Which of the following statements is TRUE?A． Every businessman possesses these four skills.B． When a striver stops his devotion to work，he will feel quite at ease.C． These basic skills are not instinctual at all.D． Mother's education has undoubted e

[单选题]Which of the following statements is true?A． Telephone was invented by a French engineer.B． Roman soldiers sent the important message by spelling out the words.C． African soldiers shouted from tower to tower to pass message.D． Only by using telephone

[单选题]Which of the following statements is true?A． The author's father built a bonfire on VE Day.B． The author's father had fought in the First World War.C． The author's father had fought in the Second World War.D． The author's father threw two chairs

[单选题]Which of the following statements is true?A． Males and females in the family took turns using the bathtub.B． Some bathtubs were big enough for many people to bathe in at the same time.C． All the women and girls of a family could bathe together standi

[单选题]Which of the following statements is true regarding simple sort techniques?A．exchange sort if frequently referred to as a bubble sort.B．exchange sort is the least expensive.C．if random data are in an array that is to be sorted ,an insertion sort will